Automate version generation

Version is now generated automatically based on git tags.
Both cases are handled: building from git tree and building tarball downloaded from github.

Works for qmake and cmake

.appveyor.yml

@@ -4,5 +4,6 @@ install:
   - set QTDIR=C:\Qt\5.12\mingw73_64
   - set PATH=%QTDIR%\bin;C:\Qt\Tools\mingw730_64\bin;%PATH%
 build_script:
+  - git fetch --prune --tags
   - qmake LimeReport.pro
   - mingw32-make