GUI fixes: error message lines, help system, and more

* fix line number offset in error messages
 - count number of #__nosave__ lines and pass 1-count to eval as first
   line number
* CRLF line endings on Windows when saving file
* Make links in info clickable (Tutorial 21 Google Group link)
 - use QTextBrowser instead of QTextEdit, setOpenExternalLinks(true)
* Make synth arg table entries link to their anchor tags
 - add anchor tags and styling in synthinfo.rb
* allow reselecting help entry after switching tabs
 - use itemPressed instead of itemSelectionChanged
* don't select all when running a workspace
 - do select all, but also setReadOnly for half a second while
   highlighting