Add compliant height, using ZINT_COMPLIANT_HEIGHT flag for back-compatibility

Rename barcode funcs to same as BARCODE_XXX name
library: barcode funcs array for dispatch, used for ZBarcode_ValidID() also
general: change is_sane() comparison to nonzero from ZINT_ERROR_INVALID_OPTION
MAILMARK: fuller error messages
CODABAR: add option to show check character in HRT
zint.h: use 0xNNNN for OR-able defines
GUI: add guard descent height reset button, add Zint version to window title,
  static get_zint_version() method, use QStringLiteral (QSL shorthand),
  use SIGNAL(toggled()), add errtxt "popup" and status bar, add icons,
  add saveAs shortcut, add main menu, context menus and actions, add help,
  reset_view() -> reset_colours(), add copy to clipboard as EMF/GIF/PNG/TIF,
  lessen triggering of update_preview(), shorten names of getters/setters,
  simplify/shorten some update_preview() logic in switch,
  CODEONE disable structapp for Version S
qzint.cpp: add on_errored signal, add missing getters, add test

frontend_qt/grpMQR.ui

@@ -26,6 +26,9 @@
        <property name="text" >
         <string>Si&amp;ze:</string>
        </property>
+       <property name="toolTip">
+        <string>Set size (version) of symbol</string>
+       </property>
        <property name="buddy">
         <cstring>cmbMQRSize</cstring>
        </property>
@@ -33,6 +36,9 @@
      </item>
      <item row="0" column="1" >
       <widget class="QComboBox" name="cmbMQRSize" >
+       <property name="toolTip">
+        <string>Set size (version) of symbol</string>
+       </property>
        <item>
         <property name="text">
          <string>Automatic</string>
@@ -65,6 +71,10 @@
        <property name="text" >
         <string>E&amp;rror Correction:</string>
        </property>
+       <property name="toolTip">
+        <string>Set percentage of capacity to use for
+error correction codewords</string>
+       </property>
        <property name="buddy">
         <cstring>cmbMQRECC</cstring>
        </property>
@@ -72,6 +82,10 @@
      </item>
      <item row="1" column="1" >
       <widget class="QComboBox" name="cmbMQRECC" >
+       <property name="toolTip">
+        <string>Set percentage of capacity to use for
+error correction codewords</string>
+       </property>
        <item>
         <property name="text">
          <string>Automatic</string>
@@ -99,6 +113,9 @@
        <property name="text">
         <string>&amp;Mask:</string>
        </property>
+       <property name="toolTip">
+        <string>Manually specify which mask to use</string>
+       </property>
        <property name="buddy">
         <cstring>cmbMQRMask</cstring>
        </property>
@@ -106,8 +123,8 @@
      </item>
      <item row="2" column="1">
       <widget class="QComboBox" name="cmbMQRMask">
-       <property name="maxVisibleItems">
-        <number>4</number>
+       <property name="toolTip">
+        <string>Manually specify which mask to use</string>
        </property>
        <item>
         <property name="text">
@@ -147,7 +164,8 @@
       <bool>false</bool>
      </property>
      <property name="toolTip">
-      <string>Use Kanji multibyte encoding for binary and Latin data</string>
+      <string>Use Kanji multibyte encoding for binary
+and Latin data</string>
      </property>
     </widget>
    </item>