support for old civicrm versions: do not launch upgrade if civicrm installer not found (used only to determine how old civicrm is..)

make the api.php include conditional to >= civicrm 3.4 (it appeared somewhere in 3.3.x, but results may vary)

deprecating civicrm-process-mailing (which wasn't working, and better to use the API directly, not write wrappers for each api call

Grazyna Jaworska authored May 16, 2012 and Mathieu Lu committed May 16, 2012

use module_enable() to enable civicrm, not drush_pm_enable(). seems to work better with provision 2.x

CRM-10193 : do not initialize the config object in _civicrm_init() : breaks civicrm-sql-cli, civicrm-sql-conf on empty databases, and overall just not necessary anyway. (and saves ~ 20% off init time)

Issue #1567616: support for the CiviCRM 4.2 upgrade mecanism. Also remove some duplicate code by calling drush_civicrm_upgrade_db_validate().

No longer forking the civicrm.settings.php.tpl file, using the standard one (was forked a long time ago, before 3.4, to support having a siteKey variable in the civicrm.settings.php. Patch your civicrm.settings.php locally if you really need this and you are running civicrm 3.3.x)

siteRoot variable does not exist anymore, so using db_user (this code should be re-synched with upstream, since sitekey management has been integrated in upstream for some time now)

Issue #1556622: allow _civicrm_init() to silently fail (return false, but do not abort) if civicrm was not found. Useful for the cache flush option.

Issue #1556622: avoid namespace issues with drush core functions, otherwise the civicrm cache would be systematically flushed, when drush_hook_cache_clear is called. Also, hide civicrm from the cache flush options, if it is not enabled.

Issue #1556622: avoid namespace issues with drush core functions, ex: civicrm-sql-cli and sql-cli by declaring explicit callbacks and renaming the functions to avoid conflict.