Description
Right now you need the pidgin-windev.sh script to "activate" the devenv by calling eval $(./pidgin-windev <devenv> --path). This isn't ideal and means you need more than just the win32-dev directory. Instead, we should create an activation script like python virtualenv does that you can source and will update the path environment variable for it as well as allow you to deactivate it.
This script should be able to determine it's location, and assuming it's in the right place it should be able to generate the paths correctly. The proper place should be the win32-dev directory as that's the part that we want to distribute. This would allow users to extract the archive and then activate it with a . win32-dev/activate and then compile like normal.
We should also set the WIN32_DEV_TOP environment variable as libpurple/win32/global.mak will use the environment variable if it is set. This would mean less tinkering for users which is great!