Trim the final newline of interactive (err) output

This removes the annoying blank line that's constantly inserted between the
output and the REPL prompt.
Extract a bit of duplicated code
Fix a docstring
Remove some code duplication
Fix error message
Remove unused local variable
Remove the unused alternative fontification functions
[Fix #671] Increase `nrepl-sync-request-timeout' to 30 seconds
Use repl buffer as connection buffer

  Ancillary changes:

 - new functions `nrepl-start-client-process' and `nrepl-start-server-process'.
 - `cider-init-repl-buffer' and `cider-create-repl-buffer' have clear cut
    separation of functionality
 - `nrepl-make-buffer-name` and all `cider-create-xxx-buffer-name` take explicit
    dir, port and host variables.
 - increase `nrepl-decode-timeout` to 0.025 for greater reliability
 - merge `nrepl--handle-process-output` into client process filter
 - remove `nrepl-connect' in favor of `nrepl-start-client-process'