Add docs/ directory, and beging to write LaTeX documentation

In theory, I can write the documentation in LaTeX, and include a script that
makes the .pdf file for the user.  Dunno how well this will work, or how much
time it will take.  Probably too much of both.
Fix collision with modified cgSymbol.pro

Because I wanted extra symbols with the ease of calling cgSymbol(), I modified
said routine to do so.  But, since cgSymbol() assumes the use of cgPS_Open,
which did not come about until after I had written mydevice.pro and myps.pro
that I use exclusively for the plots.  I had added a line into my modified
version of cgSymbol.pro to define the COMMON block _$FSC_PS_START_ and CG
structure ps_struct to appease a line in cgSymbol.pro.

Well, if one defines their IDL search path placing the distance-omnibus code
at the end, the IDL-COYOTE version of cgSymbol() is used, causing pukage.

So, I placed the line defining  _$FSC_PS_START_ and ps_struct into myps.pro
and renamed my extras version of the routine as cgSymbol_extra.pro, and shifted
any repository routines that need those extra symbols to point to my routine,
and otherwise the stock cgSymbol() will be called.

	renamed:    utils/cgsymbol.pro -> utils/cgsymbol_extra.pro
	modified:   utils/myps.pro
Merge _$FSC_PS_START_ bug fix into 'release'