Change keyboard behaviour independently of terminal emulation

[mabartibin]

I’d like to be able to adjust the behaviour of arrow keys, PgUp/PgDn, etc. on my keyboard independently of the terminal emulation (ANSI, Kaypro, etc.). The TermInfo class is an abstraction for the combination of these, but all available terminal types use kbdConv_Generic which creates WordStar commands.

It would be nice to generate Emacs keys for use with the MINCE editor, something else for TE, etc. While many of the old editors can be configured to generate various control sequences for their output, they don’t tend to support changing key bindings, and of course the old terminals didn’t have any navigation keys.

(Speaking of Emacs: picking one of the modifiers as "Meta" key and translating e.g. Alt-V to ESC V would also help. It seems at least some terminals did that when Emacs was designed)

I could hack this by adding a few new TermInfoKbdConv to terminf.cpp and then making TermInfoobjects for the combinations I’m interested in. But it seems to me that a refactoring of TermInfo into TermVideoInfo and TermKbdInfo would be a better approach.