Flesh out color in error messages.

[ekaschalk]

Colored error messages now display in hy-mode.

It might be worth reviewing/adding colors to hy.error.

hy:

=> ok
Traceback (most recent call last):
  File "/root/.virtualenvs/pop-synthvenv/lib/python3.6/site-packages/hy/importer.py", line 198, in hy_eval
    return eval(ast_compile(expr, "<eval>", "eval"), namespace)
  File "<eval>", line 1, in <module>
NameError: name 'ok' is not defined

has nothing highlighted here.

ipython:

In [1]: ok
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-2-eff5bc1ef8ec> in <module>()
----> 1 ok

NameError: name 'ok' is not defined

Has NameError highlighted red, the top dashes red, the "---->" and input-stream highlighted orange.