love.platform: give games a string so they know what they can do
With µLÖVE and iLÖVE, games might need to know more than just the version number to know what they can and can't do. So, I propose we give LÖVE a function or a variable that gives games a string, which tells them what platform they're on: "vanilla" for regular old LÖVE, "micro" for µLÖVE, "ios" for iLÖVE, etc.
This means that games that use more functionality than is specified by the µLÖVE standard and still want to work across wildly different platforms can check this.
Alternatively/additionally, the table passed to love.conf() could have an entry which the game can use to set the required platform, so LÖVE can give an error if the game wants to use features that implementation of LÖVE doesn't support.