[cmake] do not require eigen any more
[linearelliptic...block-swipdg] update eigen usage
[test.OS2014] use gtests expectation macros
[examples.linearelliptic.spe10model1] update grid provider usage
[linearelliptic.problems.OS2014] do not use trailing _ for private methods
[linearelliptic.testcases.OS2014] do not use trailing _ for private methods
[test.linearelliptic-swipdg] whitespace
[linearelliptic...block-swipdg] added missing argument
[test.OS2014] updated test structure and added nonparametric test