This patch removes setting the variable TEXPICTS in the tex tools and

This patch removes setting the variable TEXPICTS in the tex tools and
sets it in tee dvi2ps and dvipdf tools where it is needed. This means that we
can reset it to the original value at the end of the tool.

This is done by storing the .tex source file's path in the
.dvi file's Node .attribute slot and retrieving it in the dvi2ps and dvipdf
tools from the source.

I also updated the list of graphics extensions in the Latex scanner

I set up one function that gets called to run either dvi2ps or dvipdf
after setting TEXPICTS.

git-svn-id: http://scons.tigris.org/svn/scons/trunk@3523 fdb21ef1-2011-0410-befe-b5e4ea1792b1