Refactor the indexer block to be in the same package as the other block properties.
First attempt to win Race condition causing deadlock.
reduce the number of LinkedLists created by the symbol table.
Changes to allow for enablement of the indexer at project creation time - includes new project property for disabling indexer.
Fixed https://bugs.eclipse.org/bugs/show_bug.cgi?id=60791
Made ASTExpression more polymorphic to improve our footprint in COMPLETE_PARSE mode.