* fix(load): support nested objects
* feat: initial golang parser
Moves most of load.libsonnet to a Golang app for hopefully much faster
parsing (fingers crossed)
* feat(fast): nested objects, subpackages
* feat: incorporate fast mode into main binary
Moves the work done in the fast directory into the main executable,
removing the Jsonnet based parser in favor of the much faster Golang one.
Docsonnet packages previously used to be declared in a `main.docsonnet`.
Because this file basically always contains the same, it is kinda
redundant.
To avoid that, the information from there has been inlined into the main
Jsonnet file, while the parser logic will become part of the Go
application, as embedded Jsonnet.
