Skare 0.16 / (for CentOS-6)

These changes allow a built-on CentOS-5 environment to run on CentOS-6.

Perl-Only
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   * Include a source-built Perl (5.8.9)
   * Update PDL 2.4.4 to patched
      * this fixes a broken test in PDL
   * Update DBD::SQLite to 1.37 from 1.14
   * Add JSON (perl) 2.54
   * Update Date::Tie to 0.20 from 0.18
   * Add Bit::Vector 7.2 and Carp::Clan 6.04 to skare
      * needed by splat and previously part of system Perl
   * Add Pod::Usage 1.61
      * previously part of system Perl
   * Update App::Env::ASCDS to 0.04_ska
      * this local customization pins CentOS5 at DS8.5
   * Update Ska::AGASC to 3.4
      * This works with App::Env::ASCDS 0.04_ska

Library and Binary Changes
-----------------------------------------

   * Include the built xpa tools in skare
   * Add MySQL library
      * Needed by DBD::mysql
   * Add expat library
   * Include pgplot build fixes that work on CentOS 5 and CentOS 6
      * This produces no changes in current CentOS 5 build