Replace README.md with redirection page.
Add test case for [DRILL-1149].
[OPTIQ-347] In SqlRun, add '!plan' command
[OPTIQ-346] Add commutative join rule

CommutativeJoinRule is currently disabled.  Specifying "-Doptiq.enable.join.commute=true" enables CommutativeJoinRule and disables MergeProjectRule; the two together caused a planning-time explosion.

Tweak cost of joins, so that the left input contributes more to the cost than the right input (L log L vs. R). This reflects the cost of populating a hash table with the LHS. All else being equal, a join is more efficient if the smaller input is placed on the left.

Remove EnumerableJoinRel.getRows(), which was computing join row count assuming a many-to-one join. Fair enough, but it did not recognize that joining to a filtered dimension table reduces the row count of the fact-dimension join.

Fix display of a plan's provenance when one of the rule operands was a RelSubset.

Enable writing tests that provide arguments to EXPLAIN PLAN.
Eliminate duplicate conditions in RexProgramBuilder.addCondition, not RexBuilder.makeCall as previously.
Specify return type when calling RexBuilder.makeCall, if possible.
SqlRun: allow '!plan' after '!ok' for same SQL statement.
[OPTIQ-354] Change maven groupId to "org.apache.optiq"
Merge branch 'master' of https://github.com/julianhyde/optiq into retired