Merge branch 'ab/read-tree'

Code simplification by removing support for a caller that is long gone. * ab/read-tree: tree.h API: simplify read_tree_recursive() signature tree.h API: expose read_tree_1() as read_tree_at() archive: stop passing "stage" through read_tree_recursive() ls-files: refactor away read_tree() ls-files: don't needlessly pass around stage variable tree.c API: move read_tree() into builtin/ls-files.c ls-files tests: add meaningful --with-tree tests show tests: add test for "git show <tree>"