#383 Ctrl-F4 and Ctrl-F6 Windows Compatibility Enhancement

[FLS]

This is an enhancement of Ctrl-F4 and Ctrl-F6 shortcuts for more Windows compatibility:
- Ctrl-W closes the active file. For more Windows compatibility the shortcut Ctrl-F4 was added in parallel to close the active file.
- Ctrl-F6 shortcut was added to switch always directly to the next file (not using document switcher list) for more Windows compatibility.
In order to keep the consistency of shortcut mapper (only one shortcut per command), three additionally commands (or virtual keys) were added to the source code: IDM_FILE_CLOSE_2, IDC_PREV_DOC_NOLIST, IDC_NEXT_DOC_NOLIST, which are also assignable freely in the shortcut mapper.

[FLS]

NppPatch_6.1.3_CtrlF6_CtrlF4.patch

[Don HO]

In the current implementation, each command can have only 1 shortcut. It's not coherent for some commands we can define 2 (or more) shortcuts and for some we can do only with 1. User can always redefine their shortcut via shortcut mapper.