Merge branch 'fix/ModifiedArnoldi' into 'master'
Fix bug in DriverModifiedArnoldi This fixes a bug in ModifiedArnoldi, which may cause the solver to exit with ``` Fatal : Level 0 assertion violation Unrecognised value. ``` as recently reported in nektar-users. The problem happens because the iteration could be marked as converged when the number of vectors available is lower than `nvec`. See merge request !608