IDE: Refactor, move 2 methods from Main to SourceFileManager.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43590 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: Refactor 2 methods into one CheckDirIsInSearchPath. Add param IsIncludeFile.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43591 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: When adding the path of a new file to project search path, ask which build modes to add it to. Issue #23714.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@43592 4005530d-fff6-0310-9dd1-cebe43e6787f