Sort authors/maintainers for correct email assignment

[luator]

The PackageTemplate class internally sorts the authors and maintainers by their names. To ensure that email addresses are later assigned to the correct names, also sort them in the main function.

This fixes #486.

The result can be seen with the following command:

catkin create pkg foobar --maintainer Bob bob@mail.com --maintainer Alice alice1@mail.com --maintainer Alice alice2@mail.com --author Bob bob@mail.com --author Alice alice1@mail.com --author Alice alice2@mail.com
cat foobar/package.xml

Without this fix:

  ...
  <maintainer email="bob@mail.com">Alice</maintainer>
  <maintainer email="alice1@mail.com">Alice</maintainer>
  <maintainer email="alice2@mail.com">Bob</maintainer>

  ...

  <author email="bob@mail.com">Alice</author>
  <author email="alice1@mail.com">Alice</author>
  <author email="alice2@mail.com">Bob</author>
  ...

With this fix:

  ...
  <maintainer email="alice1@mail.com">Alice</maintainer>
  <maintainer email="alice2@mail.com">Alice</maintainer>
  <maintainer email="bob@mail.com">Bob</maintainer>

  ...

  <author email="alice1@mail.com">Alice</author>
  <author email="alice2@mail.com">Alice</author>
  <author email="bob@mail.com">Bob</author>
  ...

[mikepurvis]

Looks like a great change. Unfortunately, it seems like Travis is upset about linter complaints (really, we should pin our version of pyflakes so this doesn't happen all the time):

b"/home/travis/build/catkin/catkin_tools/tests/../catkin_tools/common.py:643:9: E722 do not use bare except'\n/home/travis/build/catkin/catkin_tools/tests/../catkin_tools/execution/stages.py:175:13: E722 do not use bare except'\n/home/travis/build/catkin/catkin_tools/tests/../catkin_tools/execution/executor.py:129:17: E722 do not use bare except'\n/home/travis/build/catkin/catkin_tools/tests/../catkin_tools/execution/executor.py:143:17: E722 do not use bare except'\n/home/travis/build/catkin/catkin_tools/tests/../catkin_tools/verbs/catkin_clean/cli.py:325:5: E722 do not use bare except'\n/home/travis/build/catkin/catkin_tools/tests/../catkin_tools/jobs/catkin.py:331:5: E722 do not use bare except'\n6\n"

[luator]

@mikepurvis Just to make sure I did not miss something: These are not related to my change, right?

[mikepurvis]

IMO the ideal behaviour would be to maintain the ordering supplied by the user in the original invocation— the PackageTemplate class gives no indication as to why it is the way it is:

https://github.com/ros-infrastructure/catkin_pkg/blob/e990a65c416cd34fd6ff5a24c7ac84c7398d4f63/src/catkin_pkg/package_templates.py#L74-L91

However, in the absence of changing that behaviour, we should absolutely avoid jumbling up names and email addresses.

(And yes, the linter complaints have nothing to do with you...)

[mikepurvis]

New behaviour verified, and the commit has been rebased to get a CI green light. Thanks for this fix!