assert2 0.4.0

assert!(...) and check!(...) macros inspired by Catch2, now with diffs!

[1;31mAssertion failed[0m at [1mmain.rs[0m:8:2
  [35massert[0m[35m!( [0m[36m(1 + 2) + (1 + 2) * (2 + 3)[0m [1;34m==[0m [33m(2 + 3)[0m[35m )[0m
with expansion:
  [36m18[0m [1;34m==[0m [33m5[0m


thread 'main' panicked at main.rs:8:5
assertion failed
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace