fltk from home:jonakopmann project

For openSUSE Tumbleweed run the following as root:

zypper addrepo https://download.opensuse.org/repositories/home:jonakopmann/openSUSE_Tumbleweed/home:jonakopmann.repo
zypper refresh
zypper install fltk

For 16.0 run the following as root:

zypper addrepo https://download.opensuse.org/repositories/home:jonakopmann/16.0/home:jonakopmann.repo
zypper refresh
zypper install fltk