Fixed bug where text got stuck when changing colortheme
Formatted popup window when clicking wedges to be nicer
Added/formatted information in process popup window.

Added memory usage and process owner to the popup.
'CPU usage' is replaced with 'CPU percent' and 'Memory usage'
with 'Memory percent' in order to stay consistent.
Fixed dark gray popup windows on Windows.

I set the preferences frame and the process popup frame to put all of
their widgets in a panel.

See http://wiki.wxwidgets.org/WxFAQ#Why_are_backgrounds_of_windows_ugly.2C_dark_grey_on_Windows.3F_I_want_them_like_my_dialog_boxes.
Formatted code to pep8
Added to todo