#503 ctext - Clarifications needed in the documentation

[Arjen Markus]

I would like to point out a few missing details in the
documentation of ctext:

1. You need to use the command "hightlight" when the
widget has been filled to get the colouring to show.
(Presumably also after each new addClass command)

2. You need to use unique tag names if you want more
than one regular expression to work for the same
colouring (e.g. alternative formats for comment)

3. Line numbering could interfere with the -elide
option. It appears possible to use the linemap
facilities to make the two work together, but this has
not been described in any detail.