Merge branch 'lt/case-insensitive'

* lt/case-insensitive: Make git-add behave more sensibly in a case-insensitive environment When adding files to the index, add support for case-independent matches Make unpack-tree update removed files before any updated files Make branch merging aware of underlying case-insensitive filsystems Add 'core.ignorecase' option Make hash_name_lookup able to do case-independent lookups Make "index_name_exists()" return the cache_entry it found Move name hashing functions into a file of its own Make unpack_trees_options bit flags actual bitfields