[Ann] xaLib - library to extract data from an array.

[Alex Tweedly]

Bob Sneidar and Richard Gaskin said :

> > Essentially it's for finding things in an array. You might say I could
>   > do the same thing by iterating through all the elements of an array,
>   > but what if I wanted to do multiple queries? It's easier for me to
>   > write SQL queries than it is to code repeat loops.
>
> I hear ya'.  I find myself tempted way more than I have time for to
> write an xquery-like library for working with arrays.  We could sure use
> one.
So, I was tempted too :-)

But I decide there was no need for the complexity of xquery, and it was 
better to keep it simple, along the lines of Andre's DBLib, or 
revIgniter's Database lIbrary.

Hence : xaLib  - eXtract from an Array Library
    which can be found (I hope) at github.com/alextweedly/xalib

(I may not have done everything right on github - please let me know if 
I need to fix anything).

There a script-only library, and a very simple test/demo stack as well 
as some basic documentation.

Summary:
the data is held in a LC array. You
  - (optionally) specify the matching criteria (by a series of calls to 
xaWhere)
  - (optionally) specify the ordering needed (by a series of calls to 
xaOrderBy)
  - (optionally) name that query for later re-use (xaNameQuery)
  - then run the query by calling xaQuery, which returns the set of keys 
matching your needs.
  - (optionally) make a copy of the 'interesting' data (but usually 
better not to do this).

Any suggestions / comments / contributions welcomed.

-- Alex.