calculate linespacing so as to be able to judge if a change in cursor position is text continuation.

[olivetthered]

calculate linespacing so as to be able to judge if a change in cursor position is text continuation. If the new y cursor position is several times the line spacing or in the opposite direction to the line spacing a new body of text should be generated even if the x cursor position is around the x origin for this block of text.

[olivetthered]

the basic functiond and tests for this have now been completed, all that's left to do is the actual continuation bit and finisahing off the supporting classes