add MathLib/Nonlinear in CMakeLists.txt
- move VecNormType to LinAlgEnums.h
- extend norm functions
add Picard class
add tests for Picard
remove unnecessary include
document private members
rename template parameter names and add documententation
make file ending consistent with other files
fixed indentation
Merge pull request #189 from norihiro-w/add-Picard

Picard nonlinear solver