BUG: SyncRecord mismatched delete[].

Detected by valgrind.
Merge pull request #230 from thewtex/delete-syncrecord

BUG: SyncRecord mismatched delete[].
ENH: Add ExtractMetricImageSlice.

Extract a metric image slice for examination.
Merge pull request #231 from thewtex/metric-slice

ENH: Add ExtractMetricImageSlice.