Use uniform type strings for files #94
Use lowercase for network related type strings
Use lowercase for signal constant strings
Update dns test to use lowercase strings
Move most constant handling code to new constants.c file
Use switch for num to string constant conversions
Merge pull request #95 from luvit/uniform-type-strings

R4R: Uniform type strings
Give each uv_handle type it's own metatable so method form can be used
Use lua_getmetatable to check userdata types for uv_handle and uv_stream userdata
Use registry tables to lookup all handle and stream types in one shot
Add missing NULL termators for method lists