Edit Box For Program Entry

Now that some additional GUI has been implemented, it is time to start to work on the edit box to make it more appropriate for editing a program and not just text.  The immediate goal is to accept BASIC code that is currently recognized by the parser and translator, parse and translate it and display the translation in a dock widget beside the edit box.  (A dock widget is a widget that can be moved or docked to any side of the application window or detached completely from the window.)

For an incremental compiler, the application will need to know when a line has been edited (when the user leaves a modified line) so that the line can be recompiled (for now translated), which could be several lines (by a deletion when multiple lines were selected, or a paste of several lines).  Also, the font of the edit box needs to be changed to a fixed width font and there needs to be a way to add color, for example, indicating errors and syntax highlighting of BASIC keywords and other program elements.

As seen so far, this will be accomplished with the text cursor that is part of the QTextEdit's document.  The document part of QTextEdit is one continuous string of characters, but there is a way to retrieve and replace individual lines within the document.  All this needs to be figured out, which will take place over the next several commits.

But first, with additional GUI implemented and working, this is a good place to tag for v0.3.1.  The various files (CMake, read me and release notes) were updated for this development release.

[commit a938626ffc]