Kart 0.14 release tracking

[olsen232]

Kart 0.14 is hopefully nearly here but still has a few different issues, some of which may be release-blocking:

• helper mode: sigint (Ctrl+C) not working properly: PR is here Fix sigint handling when running in helper mode #869 - PR is tricky to get right, currently is not right
• 2x disk-size bloat: copy-on-write not working at all on macos. This is due to us compiling with MAC_OS_X_VERSION_MIN_REQUIRED less than 10.12, which switches it off... either we figure out how to fix compilation to switch it on, or, we could subprocess.check_call to cp -c which does the same thing.
• 3x disk-size bloat? check if LFS objects are leaking into git ODB somehow. Found some config issues, PR is here: Fix LFS config for TIFFs, improve tests #872
• Apparently gdal hangs / takes ages creating VRTs sometimes - safer to flag this off

Quick fixes

• Update command-line help for kart import to mention rasters, double-check command-line help for kart raster-import

Minor issues found:

• is-working-copy-dirty checks are stricter than kart diff or kart status - they still report uncommitted changes even when there are only minor diffs which are suppressed
• would be nice if kart-status gave more info about conflicts (eg more than one CRS in a single dataset) than it does
• kart help import has some \b in it that are confusing to man