Update for Switch Header/Implementation (w/ patch)

[Kris Wong]

> Hmm this sound kinda dangerous for projects with thousands of files!

I had this concern at first as well.  Our server project currently has
1160 files in it, and has many instances of differing source/header file
names.  This is the project I used to test the patch, the jump was
instantaneous.  Since the project alo uses Qt, I tested cases of trying
to jump from Qt header files (that weren't a part of the project),
etc...  It never caused a lag.

> The globalNamespace()-node of the code-model contains all the entries
of all 
> files in the project combined, in the same Format a FileDom does. It
would be 
> much better trying to find the match there(the algorithm shouldn't
differ too 
> much, but could be a lot faster).

I will certainly look into this and try to do some timings.

> For example a split-view with automatic synchronization might get
unusable by 
> this patch, because automatic synchronization is automatically
performed 
> while typing, and with a big project this might result in a
significant hang 
> every half second.

I am not sure how this would affect split-view any differently than the
previous functionality.  The feature is still used in the same way and
does essentially the same thing.  Perhaps you could elaborate a bit
more?  The only time this code gets called is when the user does either
a Switch Header/Implementation or a Jump to Decl/Def.

Thanks,
Kris Wong