Proper testing

[zyzek]

The tests really need to be better. Some categories of tests to include (in no particular order):

• Functionality of each EVM operation
• Variables and lattice objects
• Def sites
• constant folding
• propagation of variable references between distant blocks
• Memory and state system (once memory_abstraction is eventually merged)
• Widening
• Stack Freezing
• Generic decompilation of a graph, checking that it has the right structure
• jump mutation / throw generation
• disassembly
• TSV output
• settings, both that they are set correctly, and that they have their desired effects