Cwltool

support Python 3.8 1212 by mr-c
improve error reporting in case of a symlink error, will also try to fix conflicts 1138 by tetron
Toolfactory experiment 1133 by tetron (might also fix a MS Windows specific bug)
Refactor main 1206 by tetron
CWLTOOL_OPTIONS environment variable support 1205 by tetron
set minimum version of future 1202 by mr-c

udocker: pull before execution so that ToolTimeLimit isn't affected 1177
Add input_required flag to main() 1169
handle error in cidfile removal more gracefully 1183
singularity: if dockerImageId is a local file, use it 1187
Push conformance badges to commonwl/conformance repository 1189
Provide cwltool_latest for badges 1192
--provenance: conformance tests fixes 1193
refactoring to support --provenance with toil-cwl-runner 1194
Fix for argument with empty prefix and separate False 1166
attempt to debug test failure on reproducible-builds.org 1197

handle solo secondaryFiles (no list) (1175) Thank you byee4 for the report!
mypy 0.720 & strict types (1171)
Tweak packing and scandeps (1167)

publicize end of life for cwltool on Python 2.7 (1153)
Add --enable-color/--disable-color (1140)
If document has an id: field, use it. (1141)
Job cache fix (1137)
report the line number for substitution errors (1154)
Don't resolve format fields on initial load of job order object. (1142)
Bump schema salad for bugfix. (1143)
quiet the memory collection warning (1161)
Stop preserving entire environment by accident (1164)

- Fix secondaryFiles v1.1 updater
- cleanups of the documentation strings
- produce a proper error message in case of a mismatched output name

As Singularity dropped support for `SINGULARITY_PULLFOLDER` in much of the 3.x series, with this release we have introduced a `CWL_SINGULARITY_CACHE` environment variable to set the location to save and discover Singularity format images converted from the Docker format containers.