Remove old metric_fu configuration
Remove hard tabs
GArray#get_element_size is no longer introspectable

Attach the g_array_get_element_size function by hand and call that.
Fix several cases of NilCheck smell
Remove FIXME and clean up assertions
Remove useless test
Remove superfluous leading slashes from .gitignore
Remove klass argument from GObject::Helper.cast_back_signal_arguments
Move #cast_back_signal_arguments to ISignalInfo
Move a FIXME to a TODO in the right location
Move methods out of GObject::Helper

- Move ::signal_callback_args to GirFFI::InfoExt::ISignalInfo
- Move ::cast_signal_argument to GirFFI::InfoExt::IArgInfo
Move GObject::Helper.signal_callback to ISignalInfo
Implement ITypeInfo#g_type
Move GObject::Helper#signal_arguments_to_gvalue_array to ISignalInfo
Move GObject::Helper.gvalue_for_signal_return_value to ISignalInfo
Eliminate two more methods from GObject::Helper

Replaces ::signal_argument_to_gvalue and ::gvalue_for_type_info.
Move GObject::Helper.signal_reciever_to_gvalue to ISignalInfo

This eliminates GObject::Helper
Explain extension modules
Some cleanups