groupby in clang
test groupby
for group by nothing case, optimize with no map
tests for groupby clang
wip groupby grappa
Merge branch 'master' into bmyerz-clang-groupby

Conflicts:
	raco/tests.py
fix flake
flake clang.py
forgot to add sql files for clang_tests
code for groupby grappalang
add "complex aggregates" like SUM(a+b) to grammar
move SimpleGroupBy to stock RA rules
use SimpleGroupBy in clang/grappalang
flake8, especially clang
fix complex aggregate datalog test
add test to clang for "complex aggregate"
fix literals in head expression
templatize the hashing operations

for at least things with _+_ and _+1
make aggregation grappa code match implementations
aggregates fixes in code gen