Log Message:
Update to dvtm-0.5.1 (patch from maintainer in private mail)

Plain ncurses doesn't seem to be supported anymore, so switch over to
use ncursesw by default and remove the corresponding PKG_OPTION.

0.5.1 changes:
 o Compile fix for missing set_escdelay function
 o Correct escape codes for HOME / END keys
 o The Makefile links against libncursesw by default, make unicode is gone

0.5 changes:
 o Scrollback support
 o 256 color support
 o Reduced latency on some keystrokes (lower $ESCDELAY value by default)
 o Statusbar should now support wide characters
 o $DVTM environment variable which is set to the current version
 o Screen lock functionality with Mod+X
 o Support for shifted arrow keys
 o Mod+? now displays the dvtm man page
 o Cygwin compile fix
 o Code cleanups and shrinkage by adding lots of static modifiers
 o Top stack layout (not compiled in by default)
 o Scripting interface over a named pipe (not compiled in by default)