[Stdlib, Spec-lib] Myst spec failures now includes path to the failure

[Jens0512]

This completes #139 and #141

require "stdlib/spec.mt"

describe("Fish") do
  describe("#swim") do
    it("moves the fish forward")do
      assert(false)
    end
  end
end

Will now print:

  Fish #swim moves the fish forward
    Assertion failed.
    Expected: true
         Got: false

In red :D

Also with this came a simple module Color with #colored which is what is used for printing red and green stuff here. To make that work, I added some lexing for escape codes (notably \e).

[faultyserver]

This is awesome stuff! I'm excited to get this in and be able to use it :)

[faultyserver]

Looks good! Thanks for all of this :)