Merge pull request #4 from gassmoeller/grain_size_dependent_rheology

Grain size dependent rheology
Merge pull request #5 from gassmoeller/grain_size_dependent_rheology

Grain size dependent rheology
add grain size reduction at phase transitions
Merge branch 'grain_size_dependent_rheology' of github.com:jdannberg/aspect into grain_size_dependent_rheology
fix bug in phase grain size reduction
Fix bug in reaction term postprocessor.
Merge branch 'grain_size_dependent_rheology' of github.com:jdannberg/aspect into grain_size_dependent_rheology
make flow law and grain size evolution parameters lists
Merge branch 'grain_size_dependent_rheology' of github.com:jdannberg/aspect into grain_size_dependent_rheology
fix viscosity limit
Merge branch 'grain_size_dependent_rheology' of github.com:jdannberg/aspect into grain_size_dependent_rheology
Add compressibility.