- PDF417/MICROPDF417: use latch not ps shift for padding when

spanning Text segments to avoid affecting 1st char of 2nd segment
- PDF417/MICROPDF417: add optimized encoding, FAST_MODE for
  previous scheme; formatting changes
- common.c/h: add `cnt_digits()`, comments in include and make more
  consistent, minor code fiddling
- DOTCODE: replace `dc_n_digits()` with new `cnt_digits()`
- test_qr: fix `test_qr_perf()`
- composite: minor code fiddling
- library: debug dump HIBC-processed input
- BWIPP: update to latest

frontend_qt/grpPDF417.ui

@@ -922,6 +922,20 @@ right row indicators and shortens the stop pattern</string>
      </layout>
     </widget>
    </item>
+   <item>
+    <widget class="QCheckBox" name="chkPDFFast">
+     <property name="text">
+      <string>&amp;Fast encoding</string>
+     </property>
+     <property name="toolTip">
+      <string>Use a faster but less optimal algorithm
+for encoding the data</string>
+     </property>
+     <property name="checked">
+      <bool>false</bool>
+     </property>
+    </widget>
+   </item>
    <item>
     <widget class="QGroupBox" name="groupBoxPDFStructApp">
      <property name="title">