this also includes support for the NoTheme,
a theme which doesn't add any color to mers'
output.
If you compile mers with --no-default-features,
the `colored` dependency will disappear and
mers_lib will fall back to NoTheme.
- fix bug where `thread` function wouldn't error when being called on a non-function
- add compile error when a function in `try` is never used, because this is almost certainly a mistake and will cause mers to unexpectedly go down the "wrong" code path.
- some small changes so mers_lib can be used in another project
- some small bugs are now fixed
- include comments in error messages (if this causes issues, use --hide-comments)
- colors should make more sense now
- error-related things moved to mers_lib/src/errors/
&v = (v, 1).sum might fail if two threads do it at the same time or something, so you can now lock the reference to ensure no other thread messes with your data while you update its value
