* configure.in: look for libncurses or libtermcap
* vte.pc.in: include other libraries (ncurses, termcap, socket, whatever) in
	the list of libraries.
* src/keymap.c(_vte_keymap_map): for Home and End, consult libncurses or
	libtermcap if we have no hard-wired mapping and there's none in the
	termcap file.  Should fix #100472, even in cases where Home and End
	vary wildly from what I've got on my box.
* src/keymap.c: rename cursor/fkey_normal to cursor/fkey_default, which makes a
	little more sense.