Update just the edit window, not the whole screen, when toggling softwrap

Original nano commit: 5010
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=5010
Original nano commit message:
	When toggling softwrap, only the edit window needs to be refreshed,
	not the entire screen.
Eliminate 'abort variable in do_browser()

Original nano commit: 5011
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=5011
Original nano commit message:
	Removing a superfluous abortion variable, and placing two comments better.
In do_redo(), rename 'undidmsg' to 'redidmsg'

Original nano commit: 5012
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=5012
Original nano commit message:
	Renaming 'undidmsg' to 'redidmsg', to be apt.
Rename ScrollDir constants from UP_DIR and DOWN_DIR to UPWARD and DOWNWARD

Original nano commit: 5013
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=5013
Original nano commit message:
	Renaming UP_DIR and DOWN_DIR to UPWARD and DOWNWARD, for clarity,
	to reduce the slight confusion with DIR meaning directory.
Rename no_replace_void() to toggle_replace_void(), and the 'dontreplace' pinotrc option to 'togglereplace'

Original nano commit: 5014
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=5014
Original nano commit message:
	Renaming 'no_replace_void()' to 'flip_replace_void()',
	to show what it actually does.
Allow 'gotodir' to be bound to different keys.

Original nano commit: 5015
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=5015
Original nano commit message:
	Adding the bindable function 'gotodir', documenting it, and also
	documenting 'tofiles' and 'flipnewbuffer', and correcting the
	description of 'gototext' (not being about the file browser).
Add 'Ins' and 'Del' keys to highlighting for pinotrc files

Original nano commit: 5016
http://svn.savannah.gnu.org/viewvc?view=rev&root=nano&revision=5016
Original nano commit:
	Showing Ins and Del as valid rebindable keys in the nanorc syntax colouring.
Convert strtosc() to operate on std::string instead of char*
Convert strtomenu() to operate on std::string instead of char*
Remove unused diralphasort() function
Remove unused nstrcasecmp() and mbstrcasecmp() functions