Fixed:
1. Added a check of the third argument of Partition to be positive.

2. Removed a rare possibility of seg fault by an unassociated poointer in tchge.

3. A recent mistake in tqfrie.f to have dropped trans1(6,6)=0.d0 .

4. The handring of F1, F2 has been wrong since 1.1.6.18.2k64 dated on Dec. 28, 2019, when the sign of K1 is fixed to positive.

5. Some possibility of production of NaN was patched in bbstrhl.f .

6. Corrected a mistake in an internal constant cave in tspin, by the previous change.

7. ElectronRadius and ProtonRadius are adjusted to the new definition.

8. Removed a pssibility to cause seg fault in itfmessage with a character string with syntax errors, such as wrong file input.

9. A bug was found in LINE["GEO"], returning meaningless data.

Changes:
1. Suppress generation of NaN in tqchge in an extreme case.

2. ExtendedTwissParameters of Emittance[] for partial ring is taken care.

3. Removed several unused variables in .f .

4. tradkf1n is created to avoid subroutine call in radiation in tracking.

5. Avoid initialzation of bsi unless calpol.

6. If SLICE in BEAMBEAM is non-positive, it is disabled. This is useful to turn off the calculation.

7. Check the fourth arg of TrackParticles within the range of the lattice length.

Added:
1. Emittance[] now takes an option Region->{begin, end} to do the caluculation for a part of the ring. The default is {1,-1}. If Region is not the entire ring, parameters such as Emittances and DampingRate, etc., are not calculated,
and return NaNs.

2. More descriptions in SADHelp, esp. for beam dynamics and transformations.