types: separate ctx

Separate the ctx object to its own field in CompatInfo, instead of doing
keymap->ctx.

The compilation functions should not have direct access to the keymap;
instead they should process the files with their own independent state
(in the *Info structs) as much as possible, and only at the end should
they be copied (i.e. commited) to the keymap. If the compilation fails,
it leaves no by-products. It's also just good form.

This was seemingly the original author's intention, but I suppose he cut
a few corners (mostly with the handling of virtual modifiers, which are
threaded through types -> compat -> symbols).

This commit is the first step and may look artificial; however the
'keymap' field will be removed shortly.

Signed-off-by: Ran Benita <ran234@gmail.com>
compat: separate ctx

Same as was done for types.

Signed-off-by: Ran Benita <ran234@gmail.com>
symbols: separate ctx

Same as was done for compat and types.

Signed-off-by: Ran Benita <ran234@gmail.com>