[ANN] sexp_processor 4.12.1 Released

sexp_processor version 4.12.1 has been released!

* home: <https://github.com/seattlerb/sexp_processor>
* rdoc: <http://docs.seattlerb.org/sexp_processor>

sexp_processor branches from ParseTree bringing all the generic sexp
processing tools with it. Sexp, SexpProcessor, Environment, etc... all
for your language processing pleasure.

Changes:

### 4.12.1 / 2019-06-03

* 1 minor enhancement:

  * Sexp#line now raises if setting w/ non-integer (eg nil).

* 3 bug fixes:

  * Fixed pt_testcase.rb for block args w/ trailing commas.
  * Fixed pt_testcase.rb for stabby proc sexps.
  * Simple fixes for STRICT_SEXP=1.