Use ant to build sphinx docs (rebased onto dev_5_0)



This is the same as gh-744 but rebased onto dev_5_0.

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With this PR, it is no longer required to use `make` to build the sphinx documentation.

- Each separate manual directory, and the top-level provide `html`, `pdf`, `clean` and `latexpdf` targets.
- Common ant logic is in `common`
- Travis uses ant to test the build

Testing:
- travis should be green
- `ant html pdf` (or `ant html latexpdf`) should match the behaviour of `make html latexpdf` and generate identical documentation

Future work:
- the make dependency can be removed from the openmicroscopy build to allow the release-all target to work on Windows