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This commit implements the .tex-based online help system in LON-CAPA. It
may be necessary to manually run loncom/build/help_graphics_converter.pl
and doc/help/rebuildLabelHash.pl after a cvs update, and
loncapa_apache.conf may need to be manually copied to /etc. (The
loncapafiles.lpml has been updated.)

After merging this, the URL http://[loncapahost]/adm/help/Foils.hlp
should display a help file.

Also, some *very* out-of-date files have been removed from the /doc
directory.

    1: A \textbf{tolerance\index{tolerance}} parameter determines how closely
    2: the system will require the student's answer to be in order to count it correct.
    3: 
    4: 
    5: For technical reasons, it is almost never a good idea to set this parameter
    6: to zero. Computers can only approximate computations involving real numbers. For instance,
    7: a computer's {[}decimal{]} answer to the simple problem $\frac{1}{3}$ is
    8: {}``0.33333333333333331''. It \emph{should} be an infinite series of 3's,
    9: and there certainly shouldn't be a {}``1'' in the answer, but no computer
   10: can represent an infinitely long, infinitely detailed real number. Therefore,
   11: for any problem where the answer is not a small integer, you \emph{need}
   12: to allow a tolerance factor, or the students will find it nearly impossible
   13: to exactly match the computers idea of the answer. You may find the
   14: default too large for some problems. 
   15: 
   16: There are
   17: two kinds of tolerance. For some answer $a$ and a tolerance $t$,
   18: 
   19: \begin{enumerate}
   20: \item an \textbf{Absolute} tolerance\index{absolute tolerance}\index{tolerance, absolute}
   21: will take anything in the range $a\pm t$. So if $a=10$ and $t=2$, then
   22: anything between 8 and 12 is acceptable.
   23:  Any number in the tolerance field \emph{without} a \textbf{\%} symbol is
   24: an absolute tolerance.
   25: \item a \textbf{Relative} tolerance\index{relative tolerance}\index{tolerance, relative}
   26: will take anything in the range $a\pm at$, where \emph{t} is interpreted
   27: as a percentage. Any number in the tolerance field \emph{followed by} a \textbf{\%}
   28: symbol is a relative tolerance. For example, $a=10$ and $t=10\%$ will accept
   29: anything between 9 and 11. 
   30: \end{enumerate}