Important change in MaskBox control

[Benoît Minisini <benoit.minisini@xxxxxxxxxxxxxxxx>]

Hi,

The MaskBox control was not reliable, so I rewrote its management code 
in the master branch.

Tell me if it is better now than before.

I hope there will not be too many regressions.

I added a new syntax, normally backward-compatible, that I named "weak" 
separator. It's a separator that does not block character insertion or 
deletion, as if it was not there. Think about the thousand separators of 
a big number.

To add a weak separator, put it into square brackets in the mask.

For example, for typing a currency:

$##<[,]###<[,]##0<!.00

There is still some bugs I'm still working on, but I wanted this code to 
be tested as soon as possible by those who use the MaskBox control a lot 
(not me!).

If this new behaviour cannot be backward-compatible, I will add some 
flag to keep the old MaskBox behaviour or use the new one, so that you 
don't have to adapt your project. And this flag may also be simply based 
on the version of the interpreter running the project.

Just tell me.

--
Benoît Minisini.