#4356: SourceBrowserMenu + #more code improving

Followed comments on 9e26fa0f26873cd821723dbdb6208f972d2d40b5
- Updated .gitignore
- Deleted Makefile (not sure why it has commited, shouldn't have been)
- As an addition added checking of opening the same file again (no mouse
slipping or double-double-clicking will call reloading of file)