removed preprocessing dependency from vis module (former dependency was only due to some deprecated code)

No modules were previously enabled by default. As a result, the
application wasn't very useful in the default configuration.

Enable the Vis module by default to make the CAMPVis application
functional out of the box. Additional modules can be marked as default
in the future using the mechanism (SET_DEFAULT_MODULES) introduced in
this commit.

Closes #144

There used to be no way to specify what other modules each module
required in order to work. This led to either compilation or linker
errors that were often not easy to understand.

Introduce a new module-level CMake variable, ThisModDependencies, that a
module can set in its CMake file to indicate what other modules need to
be enabled for it to compile and work properly. If defined,
ThisModDependencies should be a list of strings — the names of required
modules.

Once all available modules have been analysed, the collected dependency
information is used to activate (if necessary) the dependencies of every
enabled module. Transitive and circular dependencies are already
supported in this initial version of our module dependency system.

Unfortunately, when a module gets enabled in the CMake GUI, its
dependencies are only resolved once the Configure button is clicked and
CMake runs again. This is a limitation of CMake in that all
configuration happens offline and it's not possible to react to value
changes immediately.

References #144

Automatic pipeline registration would fail for certain valid ways of
declaring a pipeline:
- if the base pipeline class was qualified with a namespace
- if the pipeline inherited from additional classes
- if the declaration followed coding conventions different than CAMPVis'
  (e.g. no space before :, { on a new line)

Make the regex used to detect pipelines more permissive to handle the
above cases.

Closes #233

MdiDockableWindow has been extracted from MdiDockArea to simplify and
better structure our MDI implementation. The new class takes care of
creating all necessary representations (docked and floating window) of
widgets added to MdiDockArea and seamlessly switching between them in
response to the user's actions (window dragging, key presses, etc).

MdiDockableWindow improves our MDI implementation in two ways:
- MdiFloatingWindow and MdiDockedWindow instances shouldn't be
  interacted with directly; they're created and disposed of as needed,
  and therefore can't be used as a handle to access and modify an MDI
  window's state; MdiDockableWindow, in contrast, fits this role
  perfectly; it manages both representations of an MDI window, and as
  a result stays around as long as at least one of them is needed
- managing state transitions of many sub-windows directly in MdiDockArea
  was becoming clumsy as signal mapping and dynamic properties were
  required; having a separate widget that only has to control the state
  of one sub-window makes the code related to state transitions much
  simpler

Closing a docked MDI subwindow caused it to disappear if the MDI area
was in SubWindowView mode, but its inactive tab could still be seen in
TabbedView mode.

If a docked MDI subwindow gets closed, hide it by removing it from the
MDI area.

The "Tools" submenu lists all standard docked tools offered by the
application (i.e. "Pipeline tree", "Pipeline properties", and "Log
viewer"), and lets the user toggle their visibility.

This commit adds a simple main menu to the application. For the time being
it only has 2 submenus, "File" and "Visualizations". The latter is created
by MdiDockArea and lets users manage the visibility and placement of
canvas windows.

reverted changes from e7b11bfa: "added s_changed signal of properties also being propagated to its shared properties"
This was weak design and lead to problems with the AutoEvaluationPipeline.

Introducing usage of C++11 lambda functions instead of functors in some tbb::parallel_for blocks for better readibility

Merge branch 'log-highlighter-double-free-fix' of /mnt/bigone/git/repositories/berge/campvis into development

In its destructor, LogHighlighter first of all deleted its filter regex
explicitly, and then called `setFilterRegExp(0)`, triggering a second —
this time somewhat implicit — delete. If the filter regex pointer was
not NULL, this caused the application to crash due to a double-free.

Fix this error by not invoking `setFilterRegExp` in LogHighlighter's
destructor; the explicit delete performs the same cleanup as
`setFilterRegExp` anyways.

 * fixed 1D geometry TF editor
 * introduced OptionProperty to specify gradient computation mode
 * added s_changed signal of properties also being propagated to its shared properties
 * fixed sampling rate compensation when using adaptive sampling in simpleraycaster.frag

Fixed missing/wrong deregistration of GeometryXdTransferFcuntionEditors when their widgets are closed (and hence the GL contexts destroyed)

Merge branch 'fix-const' of /mnt/bigone/git/repositories/sebastian.poelsterl/campvis into development

Merge branch 'revert-no-tree-vrp' of /mnt/bigone/git/repositories/sebastian.poelsterl/campvis into development

    This reverts commit 442d5051.

Fixes -Wignored-qualifiers

Added -fno-tree-vrp to CMake definition, since tree-vrp optimization breaks the code for some strange reason.

Fixes -Wsign-compare

Fixes -Wignored-qualifiers

Fixes -Wswitch

Fixes -Wreorder