Property system optimizations

Property system optimizations

Profiling startup with the new effects code exposed some performance
gotchas. The objective is to reduce allocation of std::string
temporaries, especially when looking up node path names. Also, I
changed some paths to initialize strings with strings instead of char *;
this causes less allocation, at least with glibc. Also, eliminate
the old version of find_node and its helper functions by writing the
template version of find_node_aux to handle an explicit index
parameter.

Also, add const char[] as an internal property type

This doesn't actually add a new type to the property system, but allows using
character arrays as arguments to certain templates.