IDE: Refactor TProject.ReadProject and WriteProject into private methods and variables

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45411 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: Refactor. New TProjectBuildModes.LoadFromXMLConfig and SaveToXMLConfig. Move relevant code there from TProject.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45412 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: Refactor, move code from TProjectBuildModes to TBuildMatrixOptions.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45413 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: Refactor, move code from TProjectBuildModes to TBuildMatrixOptions.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@45414 4005530d-fff6-0310-9dd1-cebe43e6787f