Improve FlatFrontSimWithoutErrors

Remove errors by making the error producing functions not produce
errors.
Less buggy, and more correctly does what it says.
Todo: Make a 'perfect detector' subclass of the HiSPARC detector that
removes the errors.
Get angle between two zenith azimuth coordinates

Add function to utils to get angle between two angles.
Should support arrays as inputs.
Move gpstime and transformations into submodule
Add angle transformation functions

Function to make a rotation matrix.
Functions to convert between decimal and sexagesimal notation.
Rename variable in detector sim to be clearer
Subclass for the HiSPARC detector without errors

ErrorlessSimulation disables uncertainties, offset and responses.
Offsets are 0, no uncertainty in timing and number of particles, no
sampling effects.
Use Errorless subclass in FlatFrontSimulationWithoutErrors
Add Errorless version of GroundParticlesSimulation
Add ConeFrontSimulation

Calculates distance to shower core in frame of the shower,
then extra delay relative to a flat front.

Also fix missing import and indentation.