Abort pending postgis connections when exception occurs
  - patch from @abonnasseau
  - closes #2042
  - refs #2069
add test for render_with_detector + fix scale rendering tests - refs #2075
expression parser - avoid extra level of indirection
silence warnings in load_map/save_map tests for now
fix typo
remove unused and broken deepcopy support to be replaced in #2081 - refs #1390 and #946
benchmarks: more reasonable threaded double to string results
Merge branch '2.3.x' of github.com:mapnik/mapnik

Conflicts:
	src/deepcopy.cpp
	src/expression.cpp
	src/rule.cpp
break out benchmark suite into individual cpp