VERSION: annotated libtool shared lib version number update for 1.8.2

This commit updates the libtool shared library version numbers based
on SVN log activity on the v1.8 branch since r31337.

Comments are included to indicate *why* version numbers changed:

* "lib changed" means that some change occurred in the library
* "added interfaces" means that some APIs were added.  I usually
  provided examples of some of the APIs that were added, just to jog
  people's memories

A future commit will remove all the annotations, after we all agree
that these version number changes are correct (including removing
libmpi_usempi_ignore_tkr_so_version, which isn't used anywhere).