adding some extensions changes used by etsy
actually getting stuff to compile and tests to pass
init of safely.
catch
unit tests, simplifying matrix product methods
fix bug and add test.
add a TODO.
remove elements by, keep elements by
Merge pull request #365 from jattenberg/develop

adding some matrix extensions used by etsy
based on cr
Merge pull request #368 from xianxu/develop

Allow timeout of a user function