* Rework IBuildParser:
* Remove name() method.
* Remove enterDirectory and leaveDirectory signals.
* Allow chaining of parsers.
* Rename IBuildParser to IOutputParser.
* Implement GnuMakeParser.
* Remove entering/leaving directory related code from all other parsers
* Move filename fixup heuristic based on entering/leaving directory
massages from gnumake here from AbstractMakeStep.
* Add outputParser method to ToolChain: This removes the need to map
toolchains to BuildParser names in the BuildSteps.
* Enhance AbstractProcessStep to accept a IOutputParser to parse its output.
* Remove AbstractMakeStep.
* Set the appropriate Parsers in all classes deriving from AbstractProcessStep
and append the ToolChain's parser to the parser chain.
* Remove BuildParserFactories: There is no more need for them.
* Remove constants used to identify the BuildParsers.
* Clean up some names:
* Replace stdOut with stdOutput.
* Replace addToTaskWindow with addTask and addToOutputWindow with
addOutput. Do this wherever it is not yet clear that this will end up
in the Task/Output window.
Reviewed-by: dt
* Use Task class in addToTaskWindow(...) signal. This introduces
support for task categories into the BuildParsers.
* Add a task category for buildsystem issues.
* Update existing BuildParsers to new API and assign their
tasks to the Compile or Buildsystem task category.
Reviewed-By: dt
