Minor cleanup and refactoring.
Reorganize the defines a bit.
Give PinnedObject a public name.

It needs to be public since the macros expand to stack allocations
of it.
Recolor doc site.
Inline wrenIsBool and wrenObjectType.

Gives a significant perf boost:

binary_trees  3411  0.29s  107.72%
delta_blue    6762  0.15s  103.54%
fib           3061  0.33s  113.44%
for           6516  0.15s  106.76%
method_call   4564  0.22s   99.64%
Support "new" on lists.
Bring some more blue back into the stylesheet.