Precision: fix inconsistent behavior
Precision: cleanup
Precision: rework/cleanup (major)
LA/Precision: Matrix norms double-valued (like vectors); generic AlmostEqual support
Providers: double-valued matrix norms
Precision: rework comparisons, similar to equality before
LA: Iterative solvers: make residual stop criterium generic/shared
LA: Iterative solvers: make divergence stop criterium generic/shared
LA: Iterative solvers: make failure stop criterium generic/shared
Providers: drop unused matrix-norm work-array version, simplifications