Make a custom backend that can collect features to send through the izers before writing layer to pbf.
Minor fixes from compiler warnings.
Move stuff out of header file where possible.
Don't need `avecado_` prefix.

Class is already namespaced by `avecado::`.
Config for post-processor.

The post-processor is now configured by all parts of the program,
including the Python module, and is threaded through the appropriate
function calls and objects to be accessible when the vector tile is
made.
Added converter to use python dict as boost::property_tree::ptree.
start hooking up options for the generalizer
make use of simplify_converter, noting that it doesnt implement peucker at present
fix typo
Merge remote-tracking branch 'github/master' into mla-backend-processing
Fix tests broken in merge.
Added scaffold of new test.
Added simple test case for generalization.
Fix bug where geometry type was not preserved in simplification.
Merge pull request #13 from MapQuest/mla-backend-processing

Backend processing & generalizer