V0.2 - a whole rewrite

[WebReflection]

I wasn't particularly happy with the performance in v8 (vs jsc) so I decided to give classes a chance, instead of using the good old closure + objects literal style ...

pros

• performance now is better than @preact/signals core on both Bun and NodeJS
• no more clean files, everything is wrapped within a single file (except disposable) to avoid cyclic dependencies and whatnot
• Signal is now a class and so is Computed, which extends Signal without leaking, yet reusing, private fields (read more about protected properties)

cons

• the size is slightly bigger (75 bytes or something ... I guess we can live with it)
• it's less elegant and clean than before, yet the logic is really simple so it shouldn't be a maintenance issue/burden

Because I think perf win matters, and because RAM requirements are now way lower than before, I think I am going for this v0.2.0.