- re-enable Nim's cache globally
- add a new "nimcache" subdir for the libraries
- make sure Go doesn't try to link libnimbus.a in the dynamically linked
wrapper example
- always delete the static archive before recreating it
- rename wrapper.nim/.h to libnimbus.nim/.h
- better hygiene in libnimbus.h (include guards and C++ support)
- remove MainnetBootnodes copy, since we do include "config.nim" after all