Updating file manager functionality

Done - 0.4-F2: Add configuration for double click speed.
Done - 0.4-F4: Add configurable option for changing control panel
position.
Done - 0.4-F5: Add selection in FileManager.
Done - 0.4-F6: Add context menu in FileManager.
Done - 0.4-F7: Add file operations in FileManager.
Done - 0.4-F8: Add folder operations in FileManager.
Fixed - 0.4-B1: [Issue #1] Add window title length processing to limit
it's length.
Fixed - 0.4-B2: [Issue #2] Fix bug with empty directories in
FileManager.
Fixed - 0.4-B3: [Issue #3] Add control panel position processing for
maximizing windows.