fix misspelling. IPython <-> BPython
--no-ipython's help: BPython -> IPython
--no-bpython's help: IPython -> BPython
Change str.format() to support python 2.6.
Add missing source code marker in docs
Fixed bug in prompt choices with default arg
Added tests for prompt_choices
Removed comments
Refined test cases for prompt_choices
Refined prompt_choices
fix an 's' in docs
Fix python3 unit tests.

In python3 the unicode prefix is gone, so it's impossible to compare
a string representation in a compatible way.
Removed unused imports from unit tests.
Restored whitespace in unitests.
Merge pull request #123 from archugs/prompt_choices

Prompt choices
Merge pull request #125 from nfvs/fix_python3_tests

Fix python3 unit tests.
Merge pull request #124 from Ma233/master

fix an 's' in docs
Merge pull request #121 from fmerges/master

Add missing source code marker in docs
Merge pull request #120 from nfvs/format-python26-support

Change str.format() to support python 2.6
Merge pull request #115 from item4/misspelling

fix misspelling. IPython <-> BPython