evolvecmd: pass evolvestate object to _solve* functions
This patchs adds an argument evolvestate to _solve* functions. This will help us
in having one evolvestate object which we can pass around various functions and
keep storing what's going on.
evolve: create a state object in all case
Let's create a state object even when we are not in the continue mode. This will
help us passing the state object to rest of the functions.