Convert Lua's python data structure from list to dict

[tapple]

• Part of Create a generator for EmbeddedBuiltinDefinitions.cpp #122

A lot (all?) of the lua generators need to look up things by name, and that's easier if the internal data structure is a dict, not a list. Python-only change

The generators that need the most access to modules and classes by name are:

• Textmate Syntax file generation for LSL and SLua #120
• Generate EmbeddedBuiltinDefinitions.cpp #181