Merge branch 'hv/submodule-config'

The gitmodules API accessed from the C code learned to cache stuff lazily. * hv/submodule-config: submodule: allow erroneous values for the fetchRecurseSubmodules option submodule: use new config API for worktree configurations submodule: extract functions for config set and lookup submodule: implement a config API for lookup of .gitmodules values