Compile options in function reference pages.

Many documentation pages have "use this compile option to make this function available" errata notes and inline documentation. From Image functions to bcmath to... Well, pretty much everything optional seems to have this. Should we consider placing the required compile tags into the function pages, next to the version the function was made available in? I realize that this will add some complexity to functions where the compile options have changed, but considering the number of "errors" and "bugs" that are due to missing compiler directives, maybe this would be a Very Good Thing (tm)? We certainly won't be overloading the aesthetic on the page (there's plenty of whitespace next to the version tag.) -Ronabop -- Brought to you from iBop the iMac, a MacOS, Win95, Win98, LinuxPPC machine, which is currently in MacOS land. Your bopping may vary.