Add strict=True when invoking each line in bin/omero load

Because bin/omero load does not require a valid connection, the interactive
connection logic was potentially causing interferences. For instance, if an
interactive server askinput was escaped with Ctrl+C, the self.ctx.invoke()
call would silently fail and move to the next line of the file.
This commit fixes this issue by setting strict=True, effectively aborting
the full command if such an interruption is caused.

OME-DCO-1.1-Signed-off-by: Sebastien Besson <seb.besson@gmail.com> (github: sbesson)
Add keep going option to bin/omero load

OME-DCO-1.1-Signed-off-by: Sebastien Besson <seb.besson@gmail.com> (github: sbesson)
Replace retry-on-error by sdterr message in bin/omero load --keep-going

OME-DCO-1.1-Signed-off-by: Sebastien Besson <seb.besson@gmail.com> (github: sbesson)
Add 'load -k' test
Clarify docs/logs and reset error code
Merge pull request #2742 from sbesson/rebased/develop/12417_cli_load

Add strict=True when invoking each line in bin/omero load (rebased onto develop)