Update references to web sites, git repositories, jira, mailing lists, travis CI now that [INFRA-8413] is fixed.

Update references to jira cases from OPTIQ-xxx to CALCITE-xxx.

Expand instructions in HOWTO for publishing a release.
[CALCITE-443] getPredicates from a union is not correct
Make it more convenient to unit test RelMetadataQuery, and add some more tests for [CALCITE-443].
[CALCITE-442] Add RelOptRuleOperand constructor that takes a predicate
Progress on [OPTIQ-436] Simpler SPI to query Table
Progress 10/23.