CLI: make --mirror available in standard non-batch mode via

new routines `mirror_start()`, `mirror_outfile()` & limit
  substitutions on Unix to backslash (Windows remains the same);
  restrict "borderwidth", "textgap", "vwhitesp", "whitesp" < 100
CODEONE: fix `ceilf()` -> `C1_MULT_CEIL()` in FAST_MODE encodation
  (improves/changes some encodation)
composite: preserve `gs1_verify()` warning using `warn_level` hack;
  fix wrong name `zint_dbar_omnstk_set_height()` ->
  `zint_dbar_stk_set_height()`;
  use new `zint_micropdf_variant()` & `zint_micropdf_expand()`
  routines (see below)
MICROPDF417: move variant determination into new shareable routine
  `zint_micropdf_variant()` & expansion into `zint_micropdf_expand()`
qzint: add helper methods `setbordertypevalue()`,
  `encodedinputmode()`, `encodedoutputoptions()`,
  `ecivaluetoeciindex()` and `eciindextoecivalue()`
dbar: for performance pre-calculate `combins()` as array
coverage: add `malloc()`-type failure testing to AZTEC,
  CONTENT_SEGS, MEMORY_FILE, raster, Reed-Solomon & vector;
  numerous changes to remove unused code and test more branches
common: add `isxdigit()`
general: various code fiddlings
manual: add char names to sequence and batch format char tables;
  mention long options can be shortened (& use "--compliantheight"
  -> "--compliant");
  expand mirror explanation & document substitutions in footnote;
  workaround xecjk putting space after double quote when quoting
  cjk chars & rejig input mode examples;
  workaround html alignment bug in table gs1-enabled symbologies by
  adding extra rh dashes to header cols;
  add "figure nn: " to txt image tags via sed:
  various other small fixes and rephrasings

docs/Makefile

@@ -184,14 +184,14 @@ $(OUT_TXT) : $(SOURCE) $(SOURCE_MAN_PAGE) $(INCLUDES_TXT) $(INFRASTRUCTURE)
 			-V $(MAIN_FONT) -V $(MONO_FONT) -V $(CJK_FONT) \
 			$(TXT_OPTS) \
 			-o $(OUT_TXT)
-	# Indent Man Page sections in TOC, remove trailing spaces, echoed image tags, tbl: hashes
-	# & clean up Table captions
+	# Indent Man Page sections in TOC, remove trailing spaces, tbl: hashes,
+	# clean up Table captions & prefix Figure nos. (https://stackoverflow.com/a/60073027)
 	sed -i \
 		-e 's/^\(-   [A-Z][A-Z ]*\)$$/    \1/' \
 		-e 's/  *$$//' \
-		-e '/^\[.*\]$$/{N;N;s/\[\(.*\)\]\n\n\1/[\1]/;p;d}' \
 		-e 's/ *{#tbl:[^}]*}//' \
 		-e 's/^  : Table/  Table/' \
+		-e '/^\[[^1-9].*$$/{x;s/.*/expr & + 1/e;x;G;s/^\[\(.*\)\n\(.*\)/[Figure \2: \1/}' \
 		$(OUT_TXT)
 	# Wrap
 	sed -i '/.\{81\}/{s/.\{80\}/&\n/}' $(OUT_TXT)