Squashed commit of the following:
Update .gitignore
Fix some compile-related issues.
Add support for cursors of differing pixeldepth.
Various compile-related fixes.
graphics/nxglib: Separate cursor rendering routines in nxglib/ (like all other rendering logic). graphics/nxbe: Flesh out remaining cursor methods.
libs/libnx/nxme: Add front-end, client, message handling needed for cursor support. Still actual cursor logic yet, just message handling.
graphics/nxmu and graphics/nxbe: Add back-end message handling needed for cursor support. No actual cursor logic yet, just message handling.