remove touch command from Holmakefile since lem does that now
rewrite compile_decl again, simplify compiler_state

the rsz and renv fields were redundant: they can both be calculated from
rbvars. (the first was its length and the second a list of numbers down
from that length to 1.)

now compile_decl partitions the variables to be bound into those that
are going to shadow old ones and those that are new. it then has
separate helper functions for organising the stack in either case. the
helper functions are simpler because they know what case they're in.
theorems towards compilation of declarations

plausible compile_news_thm and compile_shadows_thm proved.
thoughts about compile_fake_exp_val and compile_dec_val.