Revision 6850

?	added some warning messages to Course Admin if permissions on DATA, log and html directories are not set correctly.
?	added refreshEquations(1) to PG to force all equation images to be recalculated.

?added AddToTexPreamble($str ) to PG  to allow short macro definitions such as    \newcommand{\myVec}[#1]{\vec{#1}}
	?	this works in images mode and in hardcopy mode.  It does not work in jsMath mode (but fails gracefully).  MathJax also fails, not quite so gracefully.