gnuscripts/lalsuite_python.am: replace @LALSUITE_BINDIR@ in Python scripts

Description

• For uninstalled scripts, this is replaced with the current build directory, so scripts will at least find executables in the same directory. The shell wrapper script makes this replacement on the fly; requires AC_PROG_MKDIR_P().
• For installed scripts, this is replaced with $(bindir).

Also includes this change:

• Add a dummy comment at start of all Python scripts without a shebang line, i.e. those not installed in $(python_exec_prefix), to keep line numbers consistent regardless of where a script is installed.

API Changes and Justification

Backwards Compatible Changes

• This change introduces no API changes
• This change adds new API calls

Backwards Incompatible Changes

• This change modifies an existing API
• This change removes an existing API

If any of the Backwards Incompatible check boxes are ticked please provide a justification why this change is necessary and why it needs to be done in a backwards incompatible way.

Review Status

Closes #480 (closed)