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

backend_qt/qzint.h

@@ -146,7 +146,8 @@ public:
 
     /* Type of border above/below/around barcode */
     int borderType() const; // `symbol->output_options | BARCODE_BIND | BARCODE_BOX | BARCODE_BIND_TOP`
-    void setBorderType(int borderTypeIndex);
+    void setBorderType(int borderTypeIndex); // Sets from comboBox index
+    void setBorderTypeValue(int borderType); // Sets literal value
 
     /* Size of border in X-dimensions */
     int borderWidth() const; // `symbol->border_width`
@@ -246,6 +247,8 @@ public:
     int encodedOption1() const; // Read-only, encoded `option_1`
     int encodedOption2() const; // Read-only, encoded `option_2`
     int encodedOption3() const; // Read-only, encoded `option_3`
+    int encodedInputMode() const; // Read-only, `input_mode`
+    int encodedOutputOptions() const; // Read-only, `output_options`
 
 
     /* Legacy property getters/setters */
@@ -323,6 +326,12 @@ public:
     bool getWidthHeightXdim(float x_dim, float &width_x_dim, float &height_x_dim) const;
 
 
+    /* Convert literal ECI to ECI combobox index */
+    static int ECIValueToECIIndex(const int eci);
+
+    /* Convert ECI combo index to literal ECI */
+    static int ECIIndexToECIValue(const int ECIIndex);
+
     /* Return the BARCODE_XXX name of `symbology` */
     static QString barcodeName(const int symbology); // `ZBarcode_BarcodeName()`