this patch updates configure.ac so that the extra macros are stored in
gnuscripts. it also updates the macros to the latest versions from the
autoconf-archive

in the style of gstreamer proper

this is being done so that a new pad named "psd" can be added that provides
the current snap-shot

this is work towards merging the collectpads object back into the main tree

I have opened a PR to add these macros to gstreamer itself, so this patch
adds #ifdef protection to the declarations here incase the patch is
accepted upstream.

- copy event handling from adder
- override template bank's instrument and channel name with info from tags