PEP 8 (mostly)

Using the `pep8` tool, this is a clean up of most, but not all, PEP 8 "violations".

Remaining style variations:

* E111 indentation is not a multiple of four
* E121 continuation line under-indented for hanging indent
 *E126 continuation line over-indented for hanging indent
* E201 whitespace after '['
* E202 whitespace before ']'
* E261 at least two spaces before inline comment
* E302 expected 2 blank lines, found 1
* E501 line too long (> 79 characters)

I also removed unnecessary braces from `if` statements.