stringptr.h: fix kdevelop breakage at the source
add C++ boilerplate to sblist.h
stringptr.h: add SPNIL macro
vario.h: add VNIL macro
logger: make some funcs take const char*
add stringptrlist_tofile
make fileparser_open filename const
make stringptrlist_add_strdup a function to prevent breakage when strdup returns 0
add stringptrlist_fromfile()
add stringptrlist_find()
stringptrlist_contains(): use stringptrlist_find()