Transition matrix functionality for compressive code

[tdcwilliams]

Separate function for kernel matrix and forcing).

• For each edge condition, output a single vector (ie combine plate terms and water pressure terms).
• NB still need a separate vector for the compressive waves.

Use book-keeping standard from SUB_TMstep_Gal.m (add in jc_inc1,2 etc to SUB_RTstep_Gal_comp_v1.m)

[tdcwilliams]

Draft code for transition matrices written now (SUB_TMstep_Gal_comp.m). To test:

• Agreement with old code (SUB_TMstep_Gal.m) when no submergence present
• Difference between old code and new one when SURGE==0
• Energy conservation not quite exact