Flap settings returned to integer

The Beech 1900 has a flap setting of 17.5 deg, but for this one
intermediate setting of one aircraft it is not worth burdening all other
aircraft with the ".0" suffix to their flap settings.
Regression option for rate_of_change added

Tried this, but it didn't make a significant improvement in results.
Retained for possible future use.
index_at_value_or_level_off  library routine extracted from flight_phase Go Around and Climbout to support its use in Approach And Landing which will benefit from this routine.
ApproachAndLanding updated to use climbout or level off as per goaroundandclimbout as an improved method of extending the go around phase - without this it is easy to created slices where the start is None.
Blend parameters accept None types in list of sources
blend_parameters now accepts None available sources
blend_parameters now accepts None available sources
Wheel Speed merging - using updated naming convention of (L) (*) and (R) (*) sources.
Merge branch 'master' of github.com:FlightDataServices/FlightDataAnalyzer
Fuel Qty Low additional test
unstaged and resolved changes
updated IAN KPV's to use Displayed App Source
Error caught in case square root is less than zero.
Merge branch 'master' of https://github.com/FlightDataServices/FlightDataAnalyzer
changed ILSLocalizerEstablished to use Approach instead of Approach and Landing sections
Merge branch 'master' of https://github.com/FlightDataServices/FlightDataAnalyzer
fix: allow for decimal flap detents

Apologies - It wasn't as easy as expected when I tried to do this last
time! This time we check whether the detent is an integer and force the
KPV name to use integers in this case. Otherwise we force a single
decimal place.
change to ILS Localizer Established to be more robust against small differences in floating point numbers when looing for frequency changes
Merge branch 'master' of github.com:FlightDataServices/FlightDataAnalyzer
Find matching cycles where possible