optimize: Allow non-power-of-2 SQTable sizes.

As SQTable used for various name space tables, it's nice memory
save measure to keep exactly as much as needed elements in table.
optimize: SQTable: Factor out size change policy, use 50% size increase.
optimize: SQVM: Preallocate roottable to hold all global functions.
optimize: sqlexer required only for compiler.
optimize: SQTable: Rehash only when inserting with no free slots.

Previously, rehash was triggered immediately after last slot was used up.
With this change, tables with 100% load factor are supported.
optimize: CreateDefaultDelegate(): Create table of exact size needed, etc.

Also, don't create same string twice.
optimize: Create _metamethodsmap of exact size needed.
optimize: Wrap RefTable methods with NO_GARBAGE_COLLECTOR.