Fix bugs & add tests/wf-alike util/lfreq, util/cstats

Fix div by zero bugs, sequint.add from empty bug, in stat try to document why of SIMD-vectorized routines better and ease actually getting that boost, add stat.range for both min & max in 1-pass.

Track cligen pm=" +- " to just "+-" change in cstats and add it to the nimble install. Also add lfreq to the nimble install. Add cligen dependency for the two utilities.

Signature edits, warning clean-up, utility tweaks, add lfreq

The big patch is a change from z:static[int] to z:static int in signatures. Also a warning clean-up and a couple of tweaks to utilities tests/wf and util/cstats as well as adding util/lfreq which is what mostly motivates the timing of this release.

Cross Nim Portability, cstats, scope fix

Various cross Nim portability work (previewSlimSystem, BadIndex, tcc wf, etc.), Add ad hoc contextual statistics filter cstats, and a minor scope fix in adix/lptabz.nim.

Bug fixes & doc clean ups

Bug fixes are mostly Nim portability Re IndexDefect and lghisto quantiles.

Doc clean-ups are a lot & varied. git log has details.

Bug fixes & minor define-controls

Fix a bad bug of histogramming x instead of unshifted x0 and make
MovingStat work with OrderStats

Guard cligen usage with defined(useCligen) {to make .nimble not lie} and
also introduce -d:portablensort to deactivate Intel-specific PEXT32/64 nsort
optimizations. { Yes, yes..should just auto-detect/cpuid/etc. }

Make a couple test programs nicer.

`del` BREAKING CHANGE + new modules

There is a breaking change here. To be more drop-in semantically for the std/(tables|sets) world, lptabz.del & ditab.del no longer raise on missing keys. (Use missingOrExcl not exceptions if you want to test for that.) Sorry for the breaking change but cross/drop-in compatibility seems more important than backward compatibility at this stage of (guessed) user base. I must have not looked carefully at std/tables.del. Apologies.

Other changes:

• Speed-up adix/stat a bit. (backend C compilers need to at least ignore gcc __attribute__ ...).
• btree.add parameter order change to default queue discipline
• Rename bist -> Bist for general Nim convention consistency.
• New Bist-based module lghisto that is an alternative to things like tDigest but supports efficient tunable approximations to moving quantiles (where data changes point-by-point).
• New module cumsum for SIMD-optimized cumulative summation (sometimes called running sums or parallel prefix sum).
• New module nsort which does a optimized radix sort. I think the "bit level digit plan" using Intel's parallel bit extraction instruction may be a novel optimization or at least application of PEXT. (Byte level analogues probably date to early IBM sorting card research, though.) Bit-level should be great for things like float32 keys with data sets of similar order of magnitude keys probably being 2-pass. There are other standard optimizations in there, too. Read the module top.

Rename adix/wstats -> adix/stat

Rename a module to a more general purpose name before much time passes (I already switched from windowed stats terminology to moving stats and the "w" no longer matches); Probably no users yet. ;-)

Also, use the new cligen/strUt.fmtUncertainMerged format. In some strict, technical sense this makes the adix package depend upon cligen, but it is only this one module. So, I am not yet encoding that dep in the nimble file.

Better punch a release for people

Really too many to enumerate; Nevertheless, a short list is:

• get sequint working.
• Get B-tree working.
• Simplify available table choices (bundling many into lptabz.nim, including compact ordered|not, sentinel key|not, etc.).
• Add several alternative hash functions.
• Add a bltab robinHood bit-linear probing table (mostly as a cache-friendly alternative to Bloom filters demo/assessment).
• Fix quite a few bugs.