Bring melodic-devel closer to ros2 branch

[mikaelarguedas]

This PR does a few things:

• comply with ROS2 linters (ABI breaking changes):
• comply with -Wpedantic and -Wextra compiler flags:
• use size_t everytime we're using a size returned by a vector
• drop compatibility mode for console_bridge < 0.3.0
• simplify branching logic in a few places

What I didnt pull from the ROS2 branch:

• use of auto, needs to be audited to be applied only where it makes sense (doesnt impact visibility and reduces amount of code) (use auto for all for loops iterating on vectors/maps #78)

What will be done in a follow-up (hopefully before releasing into melodic):

• fix constness of functions and arguments
• infer full library name based on system (prefix with lib where necessary and append proper extension)

Nices to have:

• provide STL version of all functions as alternative to boost
• PIMPL
• Visibility macros for windows
• backport fviz test from ros2 branch

[mikaelarguedas]

3.1.3 would actually be enough but I went for 3.5 as this matches ROS 2 current minimum requirement and is way below any platform targeted by melodic

[mikaelarguedas]

this should be the default on all platforms targeted by melodic but may be needed for OSX support