Native support for existing ctags file in ST3?

[tbostick]

I would like to be able to use an existing ctags file as alternative option to having ST3 index my project because:

1. very large project and I already have a script to generate the tags file for the specific directories and exclude other files/dirs
2. project includes non-standard file extensions and non-standard language extensions that are currently known to work with ctags, unknown for ST3
3. the script I use calculates tags file size for each included directory tree so I can balance tags file size vs convenience and speed
4. some generated code may include non-printable data that could conceivably confuse another indexing mechanism, already worked around this in existing tags generation script.

It would be very helpful to have manual indexing configuration:
1. index path (I use ~/tags)
2. build script (I use ~/build_tags.pl)
3. auto vs manual rebuild (I prefer to manually rebuild when necessary)