use libltc and libtimecode as static libs, and upgrade to waf 1.7

use libltc and libtimecode as static libs, and upgrade to waf 1.7

This is slightly awkward. It is important that we only link once to the static lib. Doing this at executable link time did not
work, possibly because waf insisted on putting the two static libraries at the front of the link list. So instead libardour
is now the point where linkage to these libraries occurs (and nowhere else). This should never be changed unless the change
just moves the linkage point to another location.

Also fix a bug with the libardour version tha was picked up by waf 1.7