Added support to visualize mesh partitions. The partition info is currently
set as the physical entity number in the MSH file, but it would be trivial
to change it to something else (e.g., as soon as we generalize the MSH
format to take arbitrary number of tags per element).

Explicitly say that the mesh will be incorrect if the swapping failed

Fixed one more bug for degenerate, non-recombined extrusions, that could
lead to duplicate elements.

Fix seg fault in Read_SMS

New option pane ("Helpers") with text editor and web brower commands.

Fixed degenrate tets generation (oops!)

#ifdef some platform-specific stuff

Fix unsigned int warning

Better web browser command for Unix + generalized call (permit
multiple '%s').

typo

- Split File->Open into File->Open and File->New (i.e., the file
  chooser now only accepts existing files for File->Open)

- Added "Online documentation" help menu

Fine-tune system menu bar

better name for MacOS system menu bar option

Set max quality

some more mpeg encoders + params for higher quality

Better doc for Show/Hide

-histogram was broken in batch mode

Don't output STATUSxN messages in batch mode

"Curve" -> "Line"

Set vis_input::value() to "*" be default

couple of bugs from he mailing list

- Slightly reorganized the visibility browser window (the "toggle"
  behaviour in the input field was confusing)

- added Show and Hide commands in the parser to enable scripting of
  the visibility stuff

- Moved Visibility.{cpp,h} into Common/ to avoid dependencies with the
  Graphics library in the parser

Fix rare crash due to Fl_Widget::tooltip() not actually copying the
string.

Fixed bug in DecomposeInSimplex (need to set deleted non-simplex lists
to NULL)