make identifiers self-documenting

[mk270]

much of the code has very long identifiers; however, a bunch of temporary variables and other items use single-character names. This kind of source code should be gradually fixed

(This was originally filed as "all identifiers shall be as self-documenting as reasonably possible (s, ss, ssa? wtf does this even mean?) [one caveat - beside capitalization - don't change values in enumerations]" - i.e., it is the remaining work from #27 )