Clarified behaviour around rescheduling after a demand.

Dropping of out-of-bounds additional tasks are not handled separately to out-of-bounds previously scheduled tasks.
Merge pull request #34 from hawesie/hydro-devel

Clarified behaviour around rescheduling after a demand.
Removed potential infinite loop.
Merge pull request #35 from hawesie/hydro-devel

Removed potential infinite loop.
Added dependency instructions.
Merge pull request #36 from hawesie/hydro-devel

Added dependency instructions.
Merge branch 'hydro-devel' of https://github.com/strands-project/strands_executive into hydro-devel