Update test results (ClosedField, McIlwain_L, Lstar) for expected change

Minor channges in tracing result in different output. Changes are minor
and expected. Regression tests updated.

Changelog: list key updates since previous tagged release

Changelog, HACKING, configure: updates for new release version (1.5.16)

TODO: The doxygen documentation needs revisiting. Unclear whether it
will even build right now.

Lgm_QinDenton: handle case of extrapolation due to bad data at end of…

… day for Kp/Dst

Disabled default GSL error handler, reenabled at end of function.
Check Kp, akp3 and Dst interpolation for nan return value (extrapolation).
If return is nan, replace with default value and set appropriate return
value from Lgm_get_QinDenton_at_JD.

RBSP version 2.3.0

RBSP version 2.2.0

Added "CodeVersion" tag to MagEphem outputs.

T01_01: removed debugging print statement

MagEphemFromSpice: added T01S to docstrings... was already in model o…

…ptions

Version 1.5.14

First version with thread-safe T96 model (converted to C and optimized somewhat).