Prepare release 0.3.2
Fix typo in auto/gensubst
Normalize copyright notices
Generalize ./configure result exclude patterns
Fix (and optimize) gensubst's template extraction

The sed(1) command which extracts templates is too strict. For example,
it misses template @bar@ in line

    @foo @bar@

We fix that by processing each line as follows:
1. Skip line unless it matches /^[^@]*@/.
2. Delete match. Unless line matches /^[_A-Za-z][_A-Za-z0-9]*@/ now,
   go to (1).
3. Extract and delete template. Go to (1) to process line's remainder.

Since the resulting sed(1) code is much more compact, the fix also
optimizes template extraction.

Note that ambiguous sequences (like, e.g. @foo@bar@ which has only @foo@
extracted) could be disambiguated with a helper template (e.g. @AT@)
ultimately replaced by '@'.

Closes: #22
Allow to tune the finishing mechanism

While applying the finishing mechanism to a (native) Debian package,
changes to gensubst.sed and autofinish.am were necessary to
1. not corrupt the runlevel script's INIT INFO block and
2. use templates in debhelper(1) files with relative pathnames.

Therefore, we generalize those changes by introducing make(1) variables
* FINISH_ANTE_SEDFLAGS (with '-e SEDEX' flags overriding stripping) and
* FINISH_POST_SEDFLAGS (with '-e SEDEX' flags providing special
  substitutions).

Closes: #23