[PRISM] Locations

[kddnewton]

This set of commits does a lot of stuff.

• Fixes up the brace style in prism_compile.c to be consistent.
• Stops passing around both scope_node and parser, because parser is on scope_node.
• Introduces a bunch of PUSH_* macros that are equivalent to their ADD_* counterparts but operators on pm_line_column_t structs instead of NODE * pointers. This is to allow us to pass the locations directly instead of going through dummy_line_node.
• Starts converting things over to using the new macros. This is far from done, but gets the process started.