[CALCITE-306] Standardize code style for "import package.*;"

Rename classes and packages and generally fix things up after [CALCITE-296] and [CALCITE-419].

Make many inner classes of EnumerableRules (e.g. EnumerableFilter, EnumerableFilterRule) top-level classes.

Apply a consistent formatting convention for string literals split over multiple lines.

Rename generated file org.eigenbase.resource.Resources to org.apache.calcite.runtime.Resources.

Change occurrences of "optiq" and "eigenbase" in java code to "calcite".
[CALCITE-460] Add ImmutableBitSet and replace uses of BitSet