- fixes build of image in CI (tzdata)

Resolve "Install Google Test in Image"

Closes #50

See merge request mechanics-and-materials/ae108!41

- no longer necessary (built with ae108)

- use source at /usr/src/googletest if not found
- automatically builds library in dev environment

Resolve "Check for compiler warnings in CI"

Closes #49

See merge request mechanics-and-materials/ae108!40

- enable additional warnings
- treat warnings as errors in CI

Resolve "Add Hexa8 mesh example"

Closes #47

See merge request mechanics-and-materials/ae108!39

- generates a mesh of Hexa8 elements
- granularity can be controlled via a command line parameter

Resolve "Add cuboid mesh generator"

Closes #46

See merge request mechanics-and-materials/ae108!38

Resolve "Add Timoshenko beam element"

Closes #35

See merge request mechanics-and-materials/ae108!33

- element_axis is already zero initialized

- avoids potential future name collisions

- avoids unnecessary copy

- avoids unnecessary includes in header

- reduces compile time for users

- eliminates unnecessary copies