- Small fixes to prevent compilation warnings

- Analyzers in on-demand mode now cache units that have been queried
and resolved recently, to speed up response times and reduce overhead
- Once the cache reaches its maximum size, the oldest entry is removed
upon every insertion

- Added basic obsolescence checks in QueryEngine
- REST API GET requests now output actual JSON when requested
- Other minor changes

- Fixed a bug in the QueryEngine that caused wrong cache
sections to be selected for sensor data
- Now AverageAnalyzer actually computes sensor averages

- First working version of Data Analytics Framework
- A test plugin that performs the sum and max of its input sensors was
implemented

- Subsampling behavior with delta fixed: the deltas that
are sent over MQTT are coherent with the subsampling frequency, and are
computed separately from the local high-frequency deltas
- Added exception handling when writing to sensor file sinks
- Fixed odd ProcFS behavior that led to reading constant values from
certain files by closing and re-opening every time. Overhead seems to
be negligible

- Now sensors can be configured to be automatically written to files
(sink param)
- A per-sensor subsampling feature has also been added, allowing to
decimate the frequency of readings sent to MQTT compared to those that
have been sampled
- Also fixed a bug in MQTTpusher that caused reduced message rates

- Sensors now support a "delta" field in config files. If set to "on",
differences between successive readings instead of the raw values will
be stored
- Default is "off"
- This option should only be applied to monotonic sensors
- Can be applied to perfevents as well

- Now all sensors across all plugins adopt the naming convention
cpu<CPUid>.<sensorName>, if CPU-related, or just <sensorname> otherwise
- Code to parse cpu sets used both in Perfevent and ProcFS plugins
moved up in ConfiguratorTemplate
- Misc code to format MQTT parts also moved up in ConfiguratorTemplate

- This commit reflects changes made in the master branch and should
make the eventual merge less painful

- Now all sensors across all plugins adopt the naming convention
cpu<CPUid>.<sensorName>, if CPU-related, or just <sensorname> otherwise
- Code to parse cpu sets used both in Perfevent and ProcFS plugins
moved up in ConfiguratorTemplate
- Misc code to format MQTT parts also moved up in ConfiguratorTemplate

This is the first batch of changes, more to come