make it possible to open files at a given line via quickopen

quickopen now can parse strings like "some/file:123".
When a ProjectFileData item is executed, the file "some/file" will
be opened and the cursor position set to line "123".

REVIEW: 101054
BUG: 165593

Thanks to Dmitry Risenberg for the patch!

CCMAIL: dmitry.risenberg@gmail.com