driver: make etna_compile_rs_state more flexible

Allow writing the RS command to another place except inside the
etna_surface structure (mainly useful for debugging, and preparing to
use the RS in other places such as blitting).
driver: parse ETNA_DEBUG environment variable for debug flags

This includes `no_ts` to disable tile status, and `cflush_all` to
flush before every state update and draw call.
driver: uncomment set up TS before blit

The code to set up the TS to the source surface before blit should be safe to use now.
Only change TS if it differs from the desired state (so if necessary).
Some flushing may still be needed when changing TS value we'll see
that soon enough.
fb_old: cube_companion → cube_companion_msaa

Update old replay demo to run on cubox, to check how to get MSAA to work.
tools: don't show INST_MEMs in normal state dump

Makes state dumps somewhat more readable.
driver: implement MSAA

For now, use ETNA_DEBUG="msaa4x" or ETNA_DEBUG="msaa2x" to force usage
of MSAA for screen surface (MESA may have its own way for this...).