Merge pull request #148 from bibimbop/p1

P1
Made ppqt executable and reference python2 in the shebang.
Usability -- added Undo/Redo/Find/Find Next/Find Previous shortcuts in the Edit menu.
Creates pqHelpers to store helper functions.

Moves toRoman into it.
Creates folio_to_string from code in pqPages, and stores it in PqHelpers.
Display page number and png number in status bar.

TODO: pagenum should become imagenum, and pagenum2 should become pagenum
TODO: these fields should also have a QLineEdit that appears when the QLabel is clicked on
TODO: pagenum/pagenum2 are not set until editor is clicked in
In the Notes tab, ctrl-p now adds the book page number, not the image number.
HTML Language check panel. (Work in progress)
Added command line options: version and filename.
Do not crash when the dict/ directory is not found.
Set background color of words flagged by the dictionary, instead of underlining them, which is easier to see.
Do not highlight scannos by default.
micro-optimization. It's probably faster to test a couple boolean than compute the length of a string.