Make Side-By-Side Behaviour Configurable

[GoogleCodeExporter]

I prefer to have PDF preview on left and source document on right. The 
PDFDocument::sideBySide() method is hard-coded to open the source document on 
the left and PDF on the right.

This is obviously easy to work around with the "Place on Left/Right" menu 
options, but it gets tedious when working with source documents split into 
multiple files --- each time I open a different source file, the PDF gets moved 
right again...

It would be nice to have a configuration option:

Side-by-side behaviour:
[ ] Source left / PDF right
[ ] Source right / PDF left

Or even just a hidden setting directive in
~/.TeXworks/configuration/texworks-config.txt
would be OK.

Original issue reported on code.google.com by [email protected] on 5 Jun 2014 at 6:47