Update Neovim argument in usage
neovimqtgen: print function signature

- The code generator now prints function signature is no output
  path is given
neovimqtgen: Be more specific with data type error
Neovim --embedded-mode is now --embedded
Call api method by name

- Method ids are no longer supported, the api retrieval method
  is now called vim_get_api_info()
Update metadata parsing for new format
Fix neovim_auto target in CMakeLists.txt

- The neovim_auto target was calling the wrong nvim parameter
Refactor: Rename m_supported as supported
Add debug message for unknown methods
Update generated bindings
Add support for new ArrayOf() types

- Neovim array types are now defined as ArrayOf(Type) or alternatively
  for fixed size arrays ArrayOf(Type, Length)
- This commit implements initial support for the new array types
- Fixed arrays are only support for position values i.e.
  ArrayOf(Integer,2) other combinations are not yet supported
- The vim_get_api_info() uses a generic array type, since it is not
  supported yet, the function is not being added to the bindings
Initial support for Neovim error objects

- Neovim uses arrays as error objects for functions
  that can fail [error_type, msg]
- This commit does not yet implement support for different
  error types, it only fixes the current handlers to retrieve
  the error msg (if possible)
- As a consequence the NeovimRequest class no longer passes
  errors through the finished() signal instead a new error()
  signal was added
- The generator was updated to use the new signal and the auto bindings
  were updated
- The NeovimConnector::handleMetadata function was refactored
  to use the new signal
- A new static method was added to convert msgpack into String