xyst

Move setting m_freezeflow to ChoCG::dt() from solve()

This way taking larger time steps will be closer to what the user would
expect based on the value of freezetime.

Using:

freezeflow = 2.0
freezetime= 0.1

Previous behavior:

      1:it                 2:t                3:dt
         1  2.251830812036e-02  2.251830812036e-02
         2  4.503661624072e-02  2.251830812036e-02
         3  6.755492436108e-02  2.251830812036e-02
         4  9.007323248144e-02  2.251830812036e-02
         5  1.125915406018e-01  2.251830812036e-02
         6  1.351098487222e-01  2.251830812036e-02
         7  1.801464649629e-01  4.503661624072e-02

New behavior:

      1:it                 2:t                3:dt
         1  2.251830812036e-02  2.251830812036e-02
         2  4.503661624072e-02  2.251830812036e-02
         3  6.755492436108e-02  2.251830812036e-02
         4  9.007323248144e-02  2.251830812036e-02
         5  1.125915406018e-01  2.251830812036e-02
         6  1.576281568425e-01  4.503661624072e-02
         7  2.026647730832e-01  4.503661624072e-02