Increase metacarpus joint limit of MK3 left hand's thumb

[mfussi66]

This PR aims to increase the angular limit of the metacarpus joint limit, associated to the thumb of the MK3 left hand. The modification is done according to this suggestion: robotology/icub-models#104 (comment) . The main objective of this modification is to allow better contact between thumb and index fingertips.

[mfussi66]

I'm trying to open the hand in Gazebo, but upon selecting it, i get the following error:

terminate called after throwing an instance of 'std::invalid_argument'
  what():  stoi

The steps I took were:

1. Modify the target files with the desired limit
2. launch simmechanics_to_urdf SIM_LEFT_HAND.xml --yaml simmechanics2urdf_configfile.yaml --csv-joint simmechanics2urdf_joints_configfile.csv --outputfile model.urdf
3. Copy the generated model in icub-models by following the build instructions of icub-models-generator
4. Copied the model.config file associated to model.urdf, since the step above did not do it
5. rebuilt the robotology-superbuild
6. Launched gazebo
7. selected the hand from the inserttab

[mfussi66]

Ok, now I can correctly open the hand in Gazebo and as you can see the joint limits are updated (1.396 rad ~= 80 deg).

[pattacini]

Well done @mfussi66 👍🏻
cc @gabrielecaddeo