Separate Program Change Signals

One of the next items to handle are selections of text in the edit box where multiple lines selected may be cut of deleted, or multiple lines may be pasted.  A single line change slot, even with a type, is not sufficient to handle a line changed, lines inserted and lines deleted without some involved code.

Therefore, there will be three signals, the current line changed signal (with a number and text of the line), a new lines inserted inserted (with a number and of list of strings of the lines), and a new lines deleted signal (with a number and count of the number of lines).

For now, there is only the line changed signal and lines inserted signal (for one line) and the equivalent slots in MainWindow.  The lines deleted signal will be implemented next when lines are combined due to deleting at the end of the line or backspacing at the beginning of the line.

[commit 1226e81ca4]