Updated to test Templer::Plugin::Perl + Templer::Plugin::HTML

  Added tests for the two formatters that were not previously
 tested.  Also depend upon Test::Exception to ensure that a
 missing plugin-name causes an error.
  Apply perlcritic to our test-cases too.

  This required some minor changes to the test-cases,
 mostly to avoid the bare-filehandle opening.
  Refactor to stop passing Templer::Global around.

  This is a quick and dirty migration to ensure that the chain
 of execution goes:

    * Create Templer::Global to read the config file.
    * Parse the command line.
    * Merge the variables.
    * Pass those merged variables to Templer::Site->new();

  The plugin API now takes a reference to the Site object, to find
 values and this means nothing should touch Templer::Global but the
 setup code in templer.in.

  The test suite passes, but the plugin tests still need to be updated
 to refer to Templer::Site not Templer::Global.

  Fixes #11.
  Updated the object overview.
  Document the three new methods: get/set/fields.
  Updated test suite for API change.

  The plugin-tests now refer to Templer::Site, as they should,
 rather than the older Templer::Global.
  Fixed test for non-Unix.

  This test will skip execution if /bin/ls isn't present, or
 isn't executable.
  Updated to use new API.

  The expand_variables method uses a Templer::Site object.
  Fetch the plugin by name - using mixed case too.

  This ensures that formatter-lookup isn't case sensitive.
  Added notes for porting.

  This was for ensuring all is OK on windows.
  Removed unnecessary methods.

  Now that the great-API-juggle is complete the methods here that
 are obsolete have been removed.

  Minor POD updates too.
Minor POD updates
  New release.
  Correctly execute our tests.

  I'd left the stub-code in place to skip the test; we should run
 if we find an executable /bin/ls script.
  Added more tests.

  Added trivial tests to get the layout/content, just to satisfy
 Devel::Coverage.