Previously using `dscanner --ctags -R <dir>` would output tags without
any filenames, making it pretty useless for navigating in a project.
This was due to all the syntax objects being merged into a single generic
Module, then outputting that module without a filename specified.
This fix does the following:
* Moves the CTag header output from the Module class to the proper spot in
main.d
* Renames `Module.writeCtagsTo` to `getCtags` and now returns string[]
with the prepared tag lines.
* The CTag printing functionality in main.d now gathers all tag lines
from each module, sorts, then outputs.
Note that a more optimal implementation would be fairly straightforward.
Instead of simply returning a string[], `Module.toCtags` could take a
sorted container and insert in sorted order. main.d could pass this
container to each module in turn, then output the results.