GvinFileManager bugfix.

Fixed - B13: [Issue #13] GvinFileManager error when copying directory
inside itself.
Fixed - B14: [Issue #14] GvinFileManager context menu is showing out of
the window.
Fixed - B15: [Issue #15] GvinFileManager error when delete key is
pressed.
Fixed - B16: [Issue #16] GvinFIleManager: Not properly drawing context
menu.