better add_dependencies example
(checked that no wiki tutorial quoted from it using line numbers)
Merge pull request #28 from tkruse/depend_message

fix #26 better add_dependencies example
tip for header ordering
tips on variables and installing python scripts
link to setup.py example
better catkin section
Merge pull request #29 from tkruse/templates

better comments in templates
Support Unicode characters in person names

I like my name with its umlaut, and so does Catkin now.
better docs
code style, not changing the input arg
better detection of cycle set, by pruning leaf branches.

Since we mostly work graphs that are mostly tree-like, this should reduce the set considerably.
Example for ros-base groovy with artificialy cycle between genmsg and gencpp:

Circular dependency in subset of packages, before:

  actionlib, actionlib_msgs, driver_base, dynamic_reconfigure, gencpp,
  genlisp, genmsg, genpy, geometry_msgs, message_filters, nav_msgs, rosbag,
  roscpp, roscpp_tutorials, rosgraph_msgs, rosnode, rosout, rospy_tutorials,
  rostopic, roswtf, sensor_msgs, std_msgs, std_srvs, stereo_msgs,
  topic_tools, trajectory_msgs, turtlesim, visualization_msgs

After:

Circular dependency in subset of packages:

  gencpp, genmsg
Merge pull request #31 from tkruse/better_cycles

Better cycle detection for topological sort
minor clean up (#31)
add functions to get destinations similar to the CATKIN_*_DESTINATION variables (fix #30)
add optional exclude_paths to find_packages
add optional exclude_subspaces to find_packages
fix python3 bytes/str bug in Person

`__str__()` should return a type `str()` not `bytes()`

```
from catkin_pkg.package import Person
p=Person('plop')
str(p)
```

```
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: __str__ returned non-string (type bytes)
```
Merge pull request #34 from pierriko/master

fix python3 bytes/str bug in Person
add warning when a package depends on a metapackage
escalate warnings for invalid package.xml files into exceptions (fix #4)