Resolve "Build image via Docker Compose"

Closes #68

See merge request mechanics-and-materials/ae108!60

- (re-)building Dockerfile simplifies modifications

Resolve "Add function to explicitly compute the Schur complement"

Closes #65

See merge request mechanics-and-materials/ae108!58

- computes the elements of a matrix created by asSchurComplement

Resolve "Run examples in CI"

Closes #36

See merge request mechanics-and-materials/ae108!55

- fixes error in CI

- json files do not support comments in file header
- stdout.txt contains output of test
- fixes error in CI

- fixes error in CI

- uses definition.json files in tests/*/* to detect test configurations
- add configurations for examples: Basic, CuboidMesh

Resolve "Add `Context` to manage initialization/finalization"

Closes #63

See merge request mechanics-and-materials/ae108!56

- fixes error in CI

- additional scope is no longer needed

- automatically calls PetscFinalize on destruction

Resolve "Add example that uses ForceElement"

Closes #31

See merge request mechanics-and-materials/ae108!53

- useful for testing output with larger datasets

- permits multiple types of elements
- adapt generate_xdmf for modified output

- cpppetsc's HDF5 output does not support multiple types of elements

Resolve "Remove unnecessary creation of temporaries in asInverseMatrix"

Closes #62

See merge request mechanics-and-materials/ae108!52

Resolve "Add function asInverseMatrix"

Closes #61

See merge request mechanics-and-materials/ae108!51

- new overload of solve uses existing vector to store result

- result solves Ax=y for x to compute the image of the inverse of A at y

Resolve "Add function to create a LhsTransform"

Closes #57

See merge request mechanics-and-materials/ae108!48

- minimizes risk of name collisions

Resolve "Reverse index order in asSchurComplement"

Closes #58

See merge request mechanics-and-materials/ae108!49