…2625)

* Simplified error reporting in library detection

There is no need to duplicate the preprocessResult/Err variables.
This also simplifies naming making it more straighforward.

* Remove useless targetFilePath variable

* Slight improvement of removeBuildFromSketchFiles

* Rename variables for clarity

* Removed hardcoded build.warn_data_percentage in build.options file

Also fixed the "low memory" warning printer.

* Renamed variables for clarity

* Renamed variables for clarity

* Pre-compute sourceFile fields, and save the in the includes.cache

* Added ObjFileIsUpToDate method to sourceFile

* Implemented parallel task runner

* Simplify use of properties.SplitQuotedString

The new release of the library allow ignoring the returned error.

arduino/go-properties-orderedmap#42

* Use runner.Task in GCC preprocessor

It slightly simplifies code, but also provide the basis for the next
commits.

* Parallelize library discovery phase in compile

* The number of jobs in library detection now follows --jobs flag

* Reordered properties construction for clarity

* Reordered compileFileWithRecipe for clarity

* Added integration test

* fix: libraries are recompiled if the list of include paths changes