[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.
[linearelliptic.discretizations.block-swipdg] fix CouplingAssembler
[linearelliptic.estimators.swipdg] added LocalResidualESV2007Star
[linearelliptic.estimators.swipdg] minor clean up
[linearelliptic.estimators.swipdg] add LocalResidualESV2007Star to SWIPDG
[linearelliptic.estimators.block-swipdg] add LocalResidualOS2014StarBase
[linearelliptic.estimators.block-swipdg] add eta^T_r* to BlockSWIPDG
[linearelliptic.estimators.block-swipdg] use eta^T_r* in OS2014Star
[test.linearelliptic-block-swipdg-expectations] update
[linearelliptic.discretizations.block-swipdg] add 'penalty' product
[examples.linearelliptic.OS2014] disable bindings of Spe10Model1Example
[examples.linearelliptic.OS2014] use LincombOperator in create_product()
[examples.linearelliptic.OS2014] set dune logging color to blue
[examples.linearelliptic.OS2014] add first draft of estimators
[examples.linearelliptic.OS2014] allow to set linear solver options
[examples.linearelliptic.OS2014] assemble 'penalty' product
Merge branch 'master' into OS2014
[examples.linearelliptic.OS2014] replace dangerous 'is' by '=='
[examples.linearelliptic.OS2014] add istl_sparse backend