build static debugger

[akiarie]

we're adding the ability to traverse code in a GDB-style REPL

[akiarie]

cosmetic changes to debugger/state-view (just proposals):

• there should be no label "abstract"/"actual"; this should be indicated more subtly or before the text: label
• items on the stack should print upwards in increasing order
• the return register should only appear when it has a value
• comp and vconst should now be rconst for "runtime constant"
• we should hide the whole object/offset/size stuff for now, e.g. <rconst:$0> instead of {0:<rconst:$0>}
• get int * p to appear as int *p
• change to label-oriented instead of [[ ]]
• rconst ranges should change based on props (shallow)
• new format for stack needs justified spacing