Re-jig Makefile for use on OpenBSD

Use the system's .include definitions to compile lswm.
Don't use xcb_ewmh.h

xcb-util-wm isn't yet part of Xenocara, so for now, intern any EWMH atoms
ourselves and switch over the xcb-util-wm when it's available.
Define key bindings structure

This will hold the modifier/keys as well as the commands to run when that
key is pressed.
Stubbed event_loop
Don't use const for struct declarations

Don't define the cmd_entry structures as const; we may want to modify these
later on.
WIP
Default to using XStringToKeysym()

When looking up key symbols from character strings, xcb-util doesn't have a
way of doing this.  But our old friend X11 does, and always had.

So let us bastardise that API and throw it in to the shitty limited one that
XCB provides and hope like hell it'll work.
Makefile: glob for sources

When looking for source files, just glob them.  Makes adding files to lswm a
lot simpler.
Avoid NoSymbol when looking for keysyms

If XStringToKeysym() returns NoSymbol, then we ignore it and move on to the
next binding.
WIP.
WIP
Remove ev->error_code
Finalise key bindings

This grabs all specified keys to the root window and reacts to XCB_KEY_PRESS
events.
Grab keys on all windows

When a window appears, grab the defined keys on that window.  This will
allow not only for the already established keys to work on new windows as
well as the root window, but will allow further expansion for per-client
bindings as/when they get implemented.
WIP; WNC.
Grab pointer.  WIP.
WIP
Splattering of Atoms

This starts to exercise the horrendous XCB API to intern and reply to
certain XAtoms.  No ClientMessages yet; just trying to respond to what's
there for windows which are initially managed.