- clean up dataiterator.h a bit
- clean up dataiterator.h a bit

jsilhan/libsolv,jsilhan/libsolv,jsilhan/libsolv,JacksonIsaac/libsolv,jsilhan/libsolv,jsilhan/libsolv,JacksonIsaac/libsolv,JacksonIsaac/libsolv,jsilhan/libsolv,JacksonIsaac/libsolv,JacksonIsaac/libsolv