remove FIXME file
Clean up constants.
fix mismatching function prototypes
update python interface
add prucode.hp macro library to install
revert to two events mapped by default to r31:[30-31]

This eases the case when you may want two distinct sources for signaling either
PRU0/1 on r31:[30-31].  This was the configuration before the reorganization of
event/channel/host mappings.  Note that the r31:[30-31] event must be cleared
using the correct source name (i.e. event triggered by source0 cannot be cleared
by referencing source1).
Improve PRU_PRUtoPRU_Interrupt example

Uses updated default mapping.  Adds a signal from the ARM to PRU0 before PRU0
signals PRU1 and so forth.