trunk src restructuring broke plugin activation/de-activation/and some upgrade hooks

[DJPaul]

For people running trunk, the recent restructuring where the /src/ folder was added, along with the new bbpress/bbpress.php loader file, has caused a bunch of hooks that use bbpress()->basename to break. Easiest way to see this is put some debug in bbp_activation() and then activate the plugin -- your debug won't get called.

The issue is that WordPress thinks the plugin's basename is bbpress/bbpress.php, but bbPress thinks it's bbpress/src/bbpress.php or bbpress/build/bbpress.php. This causes actions hooked to bbp_activation() and bbp_deactivation() to not work, causing much sadness and rainy weather.

Running a production version (i.e. just a renamed copy of the build folder) continues to work fine, because bbPress' basename variable is the same as what WordPress thinks it is.

I've attached a patch; due to load order, I had to adjust the basename where we set it, rather than using the filter, which would have been neater.

[DJPaul]

Oh, forgot to mention: also fixed a long-existing typo in the bbp_plugin_basenname action name.

[johnjamesjacoby]

In 5317:

Don't allow build or src in basename in bbPress:setup_globals(). Fixes problems with activation hooks. Fixes #2559. Props DJPaul.