removed python extension - not ready
Update apc submodule pull origin
Improve dependency detection and flexibility.

General prefixes like /usr/local are too ambiguous be more precise so that we know what is needed.
Wording and cosmetics
Improved cleanup and extension link inclusions.
PHP 5.2 requires flex 5.4 place it in the path
VPX isn't known in 5.2
We need libxml2 2.7.x for 5.2 to build.
A install all script with environment assist.

Helps install dependencies and does standard config.