change array rule back to use h_many

This reverts the part of commit f7dbb2ac that reworked the definition
of arrays into explicit grammar recursion in order to make 'obj'
compile with LALR. That project never came to fruition and with
packrat it causes a recursive function call for every array element,
exhausting the stack with large arrays.

Fixes #26.

This does not yet remove the explicitly recursive rules elemd and
elemr because the latter is still used by the object stream parser.