Provide a mode to not re-compile/re-test everything at every iteration

[ColinPitrat]

I find it a bit annoying that rustlings verify and rustlings watch both recompile everything at every attempt.

One option I'm thinking of is to make rustlings watch only validate the test corresponding to the changed file. Then, if it succeeds, it could redo a verify to get to the next one.

What do you think ?

[komaeda]

this has been fixed in #120 and is released in version 1.1.0!