Retain cursor position after macro expansion

When macros are expanded, the cursor jumps to the end of the text. This is annoying if the macro is inserted into the middle of the text, as the cursor must then be moved back, either with the keys or by mouse.

This JIRA will extend the javascript text field components so that they:

• track the cursor position
• enable the cursor position to be set

This can be used to move the cursor position back to where it was, prior to macro expansion. If the cursor was at the end of a macro, then it will be moved to the end of the macro expansion.

Note that web browsers don't handle cursor positioning in the same manner. This project will initially support Firefox, Chrome and Safari.