A [must_resize] and [ctx.is_pointer_over_area()] is now used to
indicate we need a resizing. This makes it so when a user is
resizing the width of Gupax, the heavy [init_text_styles()] func
will only get called once when the user hovers over the GUI.
The button size is also now set in that function so it doesn't
have to be called in every separate tab.
Define a strict list [&str; 4] of valid path endings for p2pool/xmrig.
This prevents users (for some reason) inputting a path to some
other (maybe very important) file which Gupax would have completely
overridden with the update binary. Windows paths end with [.exe].
[og: State] is now completely wrapped in an [Arc<Mutex>] so that
when the update is done, it can [.lock()] the CURRENT runtime
settings of the user and save to [gupax.toml] instead of using an
old copy that was given to it at the beginning of the thread.
In practice, this means users can change settings around during
an update and the update finishing and saving to disk won't be
using their old settings, but the current ones. Wrapping all of
[og: State] within in [Arc<Mutex>] might be overkill compared to
message channels but [State] really is just a few [bool]'s, [u*],
and small [String]'s, so it's not much data.
To bypass a deadlock when comparing [og == state] every frame,
[og]'s struct fields get cloned every frame into separate
variables, then it gets compared. This is also pretty stupid, but
again, the data being cloned is so tiny that it doesn't seem to
slow anything down.
