Add handling of new Zint API >= 2.7.0 for Zint backend and use latest

version (2.12.0) by default (issues jimevins#86 and jimevins#160, subsumes PR jimevins#164).

 - hack "FindLibZint.cmake" to use `zint -h` to get version;
   define `LIBZINT_VERSION`
 - add new API handling in `Zint` in LIBZINT_VERSION >= 20700 define,
   leaving 2.6.3 handling unchanged
 - add some new Zint barcodes and adjust style properties of various other
   Zint barcodes
 - enable check digit handling via Zint `option_2`
 - add horizontal alignment `halign` argument to `Barcode::addText()`,
   `QtRenderer::drawText()` and `DrawingPrimitiveText::DrawingPrimitiveText()`
   and use in `QtRenderer::drawText()` to cater for Zint EAN/UPC left/right
   text align of outside digits
 - guard against QT infinite loop bug in `QFontMetricsF` when point size
   < ~0.4 (MIN_POINT_SIZE)

.travis.yml

@@ -31,7 +31,7 @@ matrix:
       - sudo apt-get -y install pkgconf libqrencode-dev
       - sudo apt-get -y install barcode
       # Install zint from source
-      - wget https://downloads.sourceforge.net/project/zint/zint/2.6.5/zint-2.6.5.tar.gz && tar xzf zint-2.6.5.tar.gz && ( cd zint-2.6.5 && mkdir build && cd build && cmake .. && make && sudo make install )
+      - wget https://downloads.sourceforge.net/project/zint/zint/2.12.0/zint-2.12.0-src.tar.gz && tar xzf zint-2.12.0-src.tar.gz && ( cd zint-2.12.0-src && mkdir build && cd build && cmake .. && make && sudo make install )
       - export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH
 
     before_script:

CMakeLists.txt

@@ -126,7 +126,7 @@ endif ()
 find_package (ZLIB 1.2 QUIET)
 find_package (GnuBarcode 0.98 QUIET)
 find_package (LibQrencode 3.4 QUIET)
-find_package (LibZint 2.6 EXACT QUIET)
+find_package (LibZint 2.6 QUIET)
 # Unit testing support
 find_package (Qt5Test 5.6 QUIET)
 

backends/barcode/CMakeLists.txt

@@ -19,6 +19,7 @@ endif ()
 
 if (${LIBZINT_FOUND})
   add_definitions (-DHAVE_ZINT=1)
+  add_definitions (-DHAVE_ZINT=1 -DLIBZINT_VERSION=${LIBZINT_VERSION})
   set (OPTIONAL_ZINT ZINT::ZINT)
 else ()
   set (OPTIONAL_ZINT "")