Fix ticket #209 regarding stance numbers.

There are occasions where the order of stances on the stance/shapeshift
bar differ between Mac and PC, which causes problems in scripts that
reference stance numbers (indices).

Implement new module OvaleStance to track stance and mastery changes.
OvaleStance maps stance indices (in the stance bar) to Ovale stance names
in a locale-independent way.

The list of stance names is available by running "/ovale stance", e.g.:

    druid_bear_form
    druid_cat_form
    monk_stance_of_the_sturdy_ox
    monk_stance_of_the_fierce_tiger
    warrior_battle_stance

These stance names can be used in place of the stance indices, e.g.:

    unless Stance(monk_stance_of_the_sturdy_ox)
        Spell(stance_of_the_sturdy_ox)

git-svn-id: svn+ssh://svn.curseforge.net/wow/ovale/mainline/trunk@689 d5049fe3-3747-40f7-a4b5-f36d6801af5f