Add support for method names instead of method ids

- Msgpack-RPC uses method names rather than method ids as identifiers
  for RPC functions. Neovim is changing its API to be compatible with
  the msgpack-rpc spec.
Remove code examples
Fix unittests for neovimobjec
NeovimConnector::notification is now neovimEvent

- To be consistent with Neovim's naming, notifications are now
  called events
Add new unittest

- A broad unit test that tries to call as many methods as it can, mostly
  to detect potential pack/unpack errors
Remove NeovimConnector::startRequest()

- Removed ::startRequest() and moved function enum assignment
  into the generated code
- The idea is to bring it back later, but first we need to initialise
  an hash table (to map function names)
Add support for embedded Neovim process

- Neovim now supports --embedded allowing other processes
  to communicate with Neovim over stdin/out
- NeovimConnector::launch() can be used to start an embedded
  Neovim process
Neovim *Strings* are now QByteArrays not QString

- Following a discussion on neovim/neovim#1130 several methods in the
  API cannot guarantee that data encoding is actually &encoding, for
  now at least all methods are considered to return byte arrays.
- ready() signal waits for &encoding
- new methods encode()/decode() to convert strings using &encoding
Add doxygen documentation

- Add new target doc to create doxygen API docs
- Added some missing API documentation