Text input sanitization (take 1)

First pass at sanitizing text input in the game.

The text is now stripped of its html tags (and not only < and > ...); things like \n, \t, ... still being displayed (but not interpreted).

* Completed the _strip_html_properly_ proc to also limit the length of the text
* Removed uses of _strip_html_simple_
* Replaced input or redondant trimming/text_copying with the new unified _stripped_input_

There's still work to do on this, several procs to merge/delete.
Making a first PR now that there's still no conflicts.

Fixes #5160 
(or would if it wasn't a false positive).