stop painting standard error red
add new interactive interpreter subclass with pretty pygments traceback coloring
Incorporate new interpreter class into the main repl and use our write traceback method to send to standard error.
Fixed 341 right arrow suggestion color
Merge pull request #373 from chena/fix-341

Fixed #341 right arrow suggestion color
stop str-ing in Interp.write, send FmtStr to stderr instead
factor out redundant code from showtraceback and showsyntaxerror
add test for interpreter
Merge pull request #368 from mlauter/master

Fix #194