gplugin/gplugin

Bump the dev version to 0.36.0 as we changed API with GPluginManager being final

Also remove the doc comment for GPluginManagerClass which no longer exists.

Testing Done:
Compiled

Reviewed at https://reviews.imfreedom.org/r/1030/
if get_option('nls')
i18n.gettext(GETTEXT_PACKAGE)
else
summary('translations',
'You have disabled installation of translations which means ' +
'English will be the only available language.',
section : 'Warnings')
endif