Compatibility: fix compiler errors

[FrancoisCarouge]

Resolve three compiler warnings and errors in support of adoption into hardened projects. Found with Ubuntu 22.04 / G++ 14.2.0 / Release configuration during development of FrancoisCarouge/Kalman plotter support.

• axes_object.h:18 The class has an accessible destructor that is not virtual. Resolution: added a default polymorphic destructor for memory safety guarantees.
• common.h:609: vec variable shadows local. Resolution: variable renamed to the more specific inner_vec name.
• common.cpp:869 Return variable not used. Resolution: throw exception.

Notes:

• Formatted touched sources with the project rules.
• There remains a variety of shadowed enumeration values, keywords, and constructors. These would be non-trivial resolution here. Workaround remains to disable shadowing hardening for the respective targets with -Wno-shadow.