Package required but not available: ‘spatstat.core’

Imports includes 24 non-default packages.
Importing from so many packages makes the package vulnerable to any of
them becoming unavailable.  Move as many as possible to Suggests and
use conditionally.

See section ‘The DESCRIPTION file’ in the ‘Writing R Extensions’
manual.
Package required but not available: ‘spatstat.core’

See section ‘The DESCRIPTION file’ in the ‘Writing R Extensions’
manual.