Merge branch 'ds/config-literal-value' into ds/maintenance-part-3

* ds/config-literal-value: config doc: value-pattern is not necessarily a regexp config: implement --fixed-value with --get* config: plumb --fixed-value into config API config: add --fixed-value option, un-implemented t1300: add test for --replace-all with value-pattern t1300: test "set all" mode with value-pattern config: replace 'value_regex' with 'value_pattern' config: convert multi_replace to flags