Marking some code that isn't compatible with Mono

The equality (==) operator between types (Type class) is not supported
in Mono.
Added a measurement structure
Implemented most (if not all) of metric history

* The metric history class can record measurements.
* Values can be estimated between measurements.
* A limited number of measurements are kept (currently 360, may increase
this later).
Implemented properties and methods

Uses Linq and existing functionality from underlying MetricHistory
class.
Added most process metrics
Corrected some metric collection issues

* The linear interpolation between two measurements is now properly
calculated.
* Corrected the issue where collected metrics were stale - needed a call
to Refresh().
* Changed the names of the metrics to match what Starbound uses.
Minor adjustments
Added a property for retrieving metric names
Implemented CPU utilization monitoring
Perf messages from the server are now recorded