iframe 6.x-1.7

Bug fixes:
* fixed issue #731430: Invalid link curly brackets allowed in anchors
* fixed issue #877626: IFRAME invalid url - double quotet url in iframe-alternate html text
* fixed issue #936220: Fatal error: Call to undefined function content_notify() in iframe.install on 15 checks for existence of function content_notify from the content module, for uninstall and disable its not further required.

Code improvement:
* enforced more drupal coding standards
* replaced normal string functions with their drupal equivalent
* strlen 0 check now as empty is faster
* more cleanup with help of scripts/code-style.pl and modul coder