removing old perf tests, see [vash-benchgraph](https://github.com/kirbysayshi/vash-benchgraph)
injected code comes after vash.compile so code can know if runtime or not
VCompiler#wrapBody only applies head/foot, does not eval
tplcache is now defined in runtime, not layout helpers
small runtime cleanup
`vash.batch`, `vash.[un]install`, `vash.lookup`

`vash.batch` allows several templates to be defined in a "single" call
to `vash.compile`, and have them automatically be "installed" into the
template cache, to be later retrieved by `vash.lookup`.

In order to support this reconstitution, the `modelName` and
`helpersName` configuration values must be passed into `vash.link`,
which is now defined in the runtime, but is also used by the compiler.

`tpl.toClientString` will still handle all of this automatically.
v0.5.15-1896