rename irony-{clang-working-directory => compiler-invocation-directory}
CDB: small comments/documentation bump
CDB: privatize some functions, minor tweaks
CDB: start fresh with a better, simpler design and interface
CDB: keep track of the current completion database

Display the the current compilation database and the compile options in
CDB menus. Ugly right now but can be enhanced in the future.
CDB: put the compilation database in its own file

This allows nicer private prefixes irony-cdb-clang-complete--<xxx>
instead of irony-cdb--clang-complete-<xxx>.

When customize variables and other configurations will be added to the
compilation databases we will be able have a better customize group.
CDB: initial support for JSON Compilation Database
JSON CDB: add support for out of source database file

When using out-of-source builds with CMake the compile_commands.json
file ends up in the out-of-source build directory. Add a facility to
specify out-of-source JSON Compilation Database file.
JSON CDB: add autoload and documentation for irony-cdb-json-add-compile-commands-path
Irony: add irony-server-kill command
Fix Irony::setDebug(false).

The previous implementation would refuse to disable debugging. Probably no impact, but at least like this the code corresponds to the comment just above.
Merge pull request #139 from lehy/patch-2

fix Irony::setDebug(false)
Elisp: privatize more symbols, removal of unused functions
Diagnostics: initial support for diagnostics