captcha 7.x-1.0

Changes since 7.x-1.0-beta2:

• #2021759: When user submits a correct answer, captcha module stores in session unconditionally, disabling page cache unnecessarily
• #1002246: make 'captcha_wrong_response_counter' updating optional and disabled by default, as it is expensive performance wise (clears variable cache)
• #1909734: don't overwrite $element['#pre_render'] in captcha_element_process, just append
• #472450 by ahwebd and soxofaan: add option to render image CAPTCHA code on RTL-mode for RTL languages
• #1717854 by greggles: remove old hook_update_n implementations
• 1701050: replace strtolower() with drupal_strtolower()
• #1460538 by neochief: avoid 'Call to undefined function _captcha_required_for_user' issue on cached forms
• #1668490 by Hermes Costell: Grammatical mistake in CAPTCHA description
• #1597970 by drupalishsandip and soxofaan: PHP sucks at comparing strings that look like numbers
• Fixed some internal drupal urls (admin/config/development/performance, admin/structure/types and admin/people/permissions)
• #1555036 by Hass (part of patch): more translatable string tweaks
• #1555036 by Hass (part of patch): don't say "flush cache" but "clear cache"
• #1555036 by Hass (part of patch): translatable string tweaks
• #893810: refactored captcha_form_alter to make sure CAPTCHA's are also shown on login block on (forbidden) admin pages when needed
• #1442746: Image_captcha unique URLs make cache_menu table grow a lot
• #1479370 by Robin Millette: added isset check for undefined property stdClass::$captcha_type