v2019.11.3: 3rd bugfix release for v2019.11

• fixed issue #43: jkqtp_format() had undefined behaviour, thanks to user:Makis42
• fixed issue #41: Build error when JKQtPlotter_BUILD_INCLUDE_XITS_FONTS set to OFF , thanks to user:smistad
• fixed issue #37: CMake installs things into $PREFIX/doc/*.txt , thanks to user:certik