Added "immutable" option to LocalStorage handlers. This is to get
configuration variables out of the session. Stuff like "lane number"
or "SQL host" never changes so there's no reason to pass it around
in session. Always including ini.php provides the same definitions.
Scripts that only need this information and not REAL session values
(i.e., values that change as POS runs) can run completely in the
background.
BUGFIX: Install pages need to use immutable arg in set() calls
Show discount amount line on receipt
Merge branch 'akt-immutable-settings' into akt-master
Merge
Merge pull request #123 from CORE-POS/discount-on-plain-receipt

FYI: Show discount amount line on receipt
Merge remote-tracking branch 'origin/master' into akt-master
Initial draft module system for editing items
Merge branch 'item-modules' into akt-master