Merge pull request #226 from funkenblatt/add-open-threshold

Add support for setting open taps threshold in template taps.
Allow empty vector to be used as a generator.
Added test for empty vector input.
Merge pull request #229 from campanja/empty-vector-generators

Allow empty vector to be used as a generator.
Moved function deserialization to prepare() to fix #230
Merge pull request #231 from ipostelnik/fix-230

Moved function deserialization to prepare() to fix #230