Merge pull request #24 from HaibingShao/Add_AdaptTimeSteping

Add adapt time steping
rename accept() to finalize() and add accept() returning bool
follow the interface change
implement new accept
follow the interface change
follow the interface change
follow the interface change: accept, finalizeTimeStep
fix GNU compiler warnings
Merge pull request #36 from norihiro-w/Add_AdaptTimeSteping

add accept() and finalize() in time step functions