[TxMt] LaTeX Watch 2.4

[Robin Houston]

http://www.puffinry.demon.co.uk/LaTeX%20Watch%202.4.dmg

Changes since 2.3:
	- Warn if PostScript mode is used with a non-default previewer.
	- Expand the help file a little.
	- With TeXShop, use open_for_externaleditor on the .tex file, to work
	  around an encoding-related bug in TeXShop.
	- Add a refresh command for Skim, which works in Skim 0.5 and later.
	  This is just as well, since the automatic file-change checking is broken
	  in Skim 0.5!

Robin