replace DS_OVERRIDE and DS_FINAL by override and final, respectively
update headers (replace Albrecht -> Schindler)
[linearelliptic.discretizations.block-swipdg] please gcc
[linearelliptic.discretizations.block...] add list of products
[linearelliptic.discretizations.base] update CachedDefault

Support new solve() signature and use linear solver options in caching.
[linearelliptic.discretizations.base] update ContainerBasedDefault

Add support for the new solve() syntax.