Merge branch 'jc/maint-1.6.0-blank-at-eof' (early part) into jc/maint-blank-at-eof

* 'jc/maint-1.6.0-blank-at-eof' (early part): diff --whitespace: fix blank lines at end core.whitespace: split trailing-space into blank-at-{eol,eof} diff --color: color blank-at-eof diff --whitespace=warn/error: fix blank-at-eof check diff --whitespace=warn/error: obey blank-at-eof diff.c: the builtin_diff() deals with only two-file comparison apply --whitespace: warn blank but not necessarily empty lines at EOF apply --whitespace=warn/error: diagnose blank at EOF apply.c: split check_whitespace() into two apply --whitespace=fix: detect new blank lines at eof correctly apply --whitespace=fix: fix handling of blank lines at the eof