colcon more restrictive on project names than CMake

[Aposhian]

Is there a reason why colcon will only accept project names that have alphanumerics, dashes and underscores?

https://github.com/colcon/colcon-cmake/blob/master/colcon_cmake/package_identification/cmake.py#L165

I agree that in an ideal world, that would be a nice naming convention, but in reality some projects do not conform to that because CMake doesn't make them. Examples:

• https://github.com/eclipse/paho.mqtt.c/blob/master/CMakeLists.txt#L21
• https://github.com/sewenew/redis-plus-plus/blob/master/CMakeLists.txt#L6

Can we make the regex more lax, without breaking other things in colcon? The fallback behavior to the directory name is good, but it shouldn't happen when there is a valid CMake project name specified.