Add examples/gt_grid.pl as a demo of the grid geometry manager

[HaraldJoerg]

This is an example of the grid geometry manager, demonstrating rowspan / colspan and cell padding.
I noticed two things:

• There is no padx / pady padding to the right of the rightmost column nor above the topmost row. A comment in grid.c suggests that half of the padding should appear on either side, but as far as I understand the C code, padLeft and padX have the same value, leaving nothing left for the other side.
• The documentation of the ipadx option says "The amount must be a valid screen distance, such as 2 or '.5c'." but it does not process units like .5c . Since this is documented only for ipadx I guess this is a unwanted documentation inheritance from Tk rather than a missing feature of Prima.

A Screenshot:

[dk]

Hello Harald,

I think I've got the padx/pady fixed - do they look ok now?

/dk

[HaraldJoerg]

Hello Dmitry,
The spacing is now as documented, thanks!