Several fixes to KEVM prover

[ehildenb]

This is a handful of fixes/improvements to the KEVM prover.

• --debug and --[no-]-minimize arguments are improved slightly.
• We use #gas(_) infinite gas in initial state for Solidity-generate proofs, which makes the branching that happens in a given proof significantly less.
• Remove a few lemmas about Cmem which are unsound, and are somewhat redundant.
• Avoids questionable lemmas about Cgascap interacting with #gas, removing several tests.
• Adds lemma about #allBut64th.

[ehildenb]

Mostly subsumed.