Don't use malloc in S2. Also don't overwrite S2Cell's v-table in S2's region covering algorithm
Missing include
Removed Candidate::num_children field
Merge branch 'v1.15.x' into daniel_3201
Merge branch 'v1.15.x' into next
Extends `map` to be variadic
Improves error messages and fixes review feedback
Fixes evaluation order and tests
Fixes include order
`order_by` accepts an optarg. Fixes #3220
Support variadic boost::variant

Review 2214
Related to #3044
merge of #711 Some of the driver tests test the installed driver
Merge pull request #3221 from grandquista/next

`order_by` accepts an optarg. Fixes #3220
Merge branch 'next' into sam_2134_iii