Improve interactive mode

[jabraham17]

Interactive mode is currently very rudimentary and hacked on top, should explore better first-class support

Should function similar to gdb with the command line kicking into interactive mode after a trigger or starting in interactive with something like -i

support single stepping, breakpoints, ebreaks, etc

[jabraham17]

After some rumination, this is going to involve a lot and requires a lot of design work. Deprioritizing it for now to work on other things, namely documentation and tests

[jabraham17]

More design thoughts

pause should execute immediately, it should be installed as a callback
dump should execute immediately unless specified

Essentially, need a way to differentiate between installing callbacks on an event(s) and calling the function immediately. Some, like pause, only make sense as a callback. Some, like single stepping, only make sense immediately. But others like dump would be valid in both contexts.

I like the idea of a modifier that can be applied to any keyword, something like keyword/MODIFIER. Then someone could write dump/i for immediate execution and dump/d for delayed. Definitely a temporary syntax, but would add a nice synergy with #51. It would be a semantic error to use an invalid modifier for a keyword (pause/d would be a semantic error). I could pick a reasonable default modifier, for the interactive shell default would be instant, while for the cli it would be delayed (as immediate doesn't make sense).

As a side note with #51, multiple modifiers could be chained as keyword/MOD/MOD/....

Right now the -control command line option and the interactive mode share a parser and actions. I like this syntax, as it adds some nice symmetry. But it doesn't make sense to execute commands immediately from the command line. Maybe a way around this is to use the same parser/grammar, but only enable a limited subset to the cli.

[jabraham17]

add ability to modify registers and memory

[jabraham17]

Instead of adding new syntax, I could reuse the old one. If on is specified, then define it as a callback. If no on, then execute it immediately. In the CLI, where only callbacks are supported, support a default on statement (the current implemention)

[jabraham17]

Add support to print ranges of registers, or even whole register classes at once

[jabraham17]

This was unfortunately not full completed

[jabraham17]

subsumed by #92