bsim: added memory view.
bsim: added stack display.
Minor memory view cleanups.
bsim: cleaned up the simulation control toolbar.
Added a key to the memory view.
Implemented .options.
Added undo feature. Kinda slow, not quite complete.
Moved memory into BSim.Beta.Memory.
Migrated from byte storage to word storage (maybe faster).
Merge branch 'master' into bsim-fs
Begin filesystem support.
Added memory protection and runtime error reporting.
Merge branch 'bsim' into bsim-fs

Conflicts:
	bsim/bsim.html
Fix error in memory writing.
Merge branch 'bsim' into bsim-fs
More bsim fs work that doesn't work because the filesystem is dud.
Can now assemble .included files mostly correctly.
Assorted UI improvements.
More UI improvements and bugfixes.
Initial work on doing checkoffs (tty only)