Tagging release v2.4.2

Tagging release v2.4.1

Tagging release v2.4.0

Fix Dockerfile for 2.3.5 release

Release v2.3.4

coronavirus

* n4 bug fixes
* Unsharp mask filter added to ImageMath
* Bug fixes for ImageMath morphological operators
* Command line arg bug fixes and improvements for N3BiasFieldCorrection, antsRegistration, antsApplyTransforms, antsMotionCorr
* Option to install libraries only for more compact ANTsR builds
* Multiple code updates for C++11
* DOC: none sampling strategy
* ITKv5 compatibility
* cmake improvements for containers, distribution, etc

WIP: try to resolve undefined version issues

latest/nightly version, may be unstable

Merge branch 'master' of github.com:stnava/ANTs

...

ENH: Add clarification.