lib/unicore/README.perl: Update

This changes this to conform to changes in Unicode 6.2
perluniprops: Add correct ignored files docs

Unicode furnishes various files that Perl ignores.  perluniprops lists
these, with a brief reason of what they are for and why they aren't used
by Perl.  Two files weren't listed, and one had a typo in the name and
an inadequate description.
mktables: Do some table-driven code generation

The Unicode Character Database consists of many files in various
different formats.  mktables has a single routine that processes the
most common format type.  Files with different formats are run through
filters to transform them into this format, so that almost all end up
being handles by this common function.

This commit adds a way of specifying the format for one of the other
format types, and then automatically generating the code to do the
transformation.  This doesn't work if the file has lines that have
special cases, such as if there is a known typo in it; the current
scheme can be used for those.

Unfortunately, all but one of the candidate files in Unicode 6.2 aren't
suitable for this table-driven approach.  But a second one is coming in
6.3, and I anticipate more in the future, as Unicode has tightened their
quality control significantly in recent releases.
mktables: Fix logic with binary vs enum properties

The code was confused about what certain variables signified, and raises
erroneous warnings at other times.  These bugs did not show up until
compiling Unicode 6.3.
Upgrade to Unicode 6.3