Add ability to define some cosntants in WP_CONFIG if desired
Detect cache enabled from WordPRess settings.
Allow cache config to be set in WP_CONFIG.PHP
Cart Widget will now respect cache detection setting.
Check using $cache_enabled setting removed becuase that setting can't be found in WordPress documentation.
WP_CACHE defined constant user per documentation here http://codex.wordpress.org/Editing_wp-config.php#Cache
meta key translation for future upgrade implementation begins
Changed constant to WPSC_PAGE_CACHE_IN_USE from WPSC_DONT_CACHE for clarity
added inline comment about caching constant
Merge remote-tracking branch 'upstream/master' into wp-cache-detection

Conflicts:
	wpsc-includes/wpsc-meta-visitor.php
Merge pull request #908 from JeffPyeBrook/wp-cache-detection

Control cached cart widget based on detecting cache enabled from WordPress settings
Avoid unnecessary queries to DB.

Collect IDs from users to be removed and then removed the users and their metadata in single queries, instead of running two queries for every user. This is much faster and reduces memory consumption when you have big quantities of users that haven't been deleted previously.
Merge pull request #913 from andrezrv/av-master

Avoid unnecessary queries to DB.
Fixed 2 typos in database-template
Merge pull request #915 from JeffPyeBrook/pr-reactive-error-message

Fixed 2 typos in database-template
Add WPSC_Claimed_Stock class and functions.
Use WPSC_Claimed_Stock class and functions.
Use time constants introduced in WordPress 3.5
Follow WordPress coding standards for whitespace.
Allow wpsc_convert_time_interval_to_seconds() to handle minutes and years.
Add 'wpsc_stock_keeping_time' and 'wpsc_stock_keeping_interval' filters.
Add and use wpsc_get_stock_keeping_seconds() function with 'wpsc_stock_keeping_seconds' filter.
Move wpsc_convert_time_interval_to_seconds() to misc.functions.php
WPSC_Claimed_Stock::submit_claimed_stock() now accepts WPSC_Purchase_Log object or ID.