Changed the interface and implementation of realloc_r2lu.

The new interface avoids the necessity to use temporary arrays.
I also added a simple documentation header.
Removed the trailing underscore from several module names
Added a simple event handler
Added a first implementation of logical operators on events
Usage examples of events and their logical operators
Documentation for initialize_x
Some ifort bugs were fixed, I updated the relevent example file
Merge branch 'dev' of github.com:pwl/fpde2 into dev
Changed the variable names in methods to self for actions and events.
Added the start and stop implementation to event_machine

- event_machine now calls try_execute and try_test instead of execute and test
- added start and stop methods to event_machine
- added a common ancestor to event and action with methods try_stop and try_start
- added try_execute to action and try_test to event
Added header file for events and actions
Added headers for icicles and generic_functions