Switch to yaml.safe_load(_all) to prevent YAMLLoadWarning

[mbuijs]

Fixes #1686.

In yaml/pyyaml#265 it's stated that safe_load always existed for this reason, I did a quick double check and it traces back at least to 2006, so this might even be safe to backport to older releases.

[dirk-thomas]

Thanks for the patch. Can you maybe also update the other places in this repo where these functions are used?

[mbuijs]

I can have a look. Would you prefer this also to be updated in tests?

[dirk-thomas]

Would you prefer this also to be updated in tests?

Yes, that would be good.

[mbuijs]

So I had not realized about the following (from https://wiki.ros.org/rosparam):

There are also special converters for angle radian/degree representations. Any Python-legal mathematical expression can be used with the radian value, with pi used to represent pi.

I'm doing some more changes to support this functionality while using the SafeLoader provided by pyyaml.

Furthermore I'll also try to see if there are other places where more features than the SafeLoader provides, so far I had just done a rapid search and replace...

[mbuijs]

Additional question: which other tools aside of rosparam and roslaunch should have the ability to do the degrees and radians conversion functionality when evaluating YAML strings?

Edit: never mind, I see that also currently it is only supported in these 2, so I'll stick to that.

[mbuijs]

So tests are passing now.
My experience with python is limited, I'm open to feedback, especially on how I applied the change in rosparam and roslaunch

1. attempting to not change the SafeLoader instance in PyYAML
2. adding the convencience functions yaml_load and yaml_load_all inside rosparam.

[marting87]

Changes look to me, since I'm getting a lot of YAMLLoadWarning in my console I hope to see this merged.

[mbuijs]

@ros-pull-request-builder retest this please

[mbuijs]

@dirk-thomas I processed your remarks and all checks have passed. Would you mind doing another check and merging if it's good?

[dirk-thomas]

Thank you for iterating on this.