Cleanup and bugfix the txtinfo plugin
Cleanup and bugfix the txtinfo plugin

Contents:
- fix file descriptor leaks if initialization find's an error
- remove ipc_open and ipc_socket_up away. We use -1 in the respective
  file descriptors for "invalid".
- killed unused variables and return types
- killed trivially duplicated code
- localized variable defintions
- added a few "const"
- removed superflous #include's
- Some minor coding style issues.

servalproject/olsr,diogomg/olsrd,nolith/olsrd,brabander/olsr,ralisi/olsrd_cl_roam,sebkur/olsrd,diogomg/olsrd-binary-heap,cholin/olsrd,duydb2/olsr,servalproject/olsr,zioproto/olsrd,duydb2/olsr,diogomg/olsrd-binary-heap,tdz/olsrd,brabander/olsr,cholin/olsrd,brabander/olsr,servalproject/olsr,tdz/olsrd,tdz/olsrd,diogomg/olsrd,zioproto/olsrd,ralisi/olsrd_cl_roam,ninuxorg/olsrd,zioproto/olsrd,sebkur/olsrd,diogomg/olsrd-binary-heap,zioproto/olsrd,duydb2/olsr,nolith/olsrd,sebkur/olsrd,ralisi/olsrd_cl_roam,servalproject/olsr,duydb2/olsr,duydb2/olsr,diogomg/olsrd-binary-heap,diogomg/olsrd,nolith/olsrd,ninuxorg/olsrd,acinonyx/olsrd,cholin/olsrd,ralisi/olsrd_cl_roam,ninuxorg/olsrd,diogomg/olsrd,sebkur/olsrd,diogomg/olsrd,servalproject/olsr,duydb2/olsr,zioproto/olsrd,duydb2/olsr,acinonyx/olsrd,diogomg/olsrd-binary-heap,duydb2/olsr,cholin/olsrd,nolith/olsrd,diogomg/olsrd,sebkur/olsrd,servalproject/olsr,tdz/olsrd,diogomg/olsrd-binary-heap,ninuxorg/olsrd,acinonyx/olsrd,cholin/olsrd,acinonyx/olsrd,tdz/olsrd,ninuxorg/olsrd,sebkur/olsrd,brabander/olsr,diogomg/olsrd-binary-heap,acinonyx/olsrd,nolith/olsrd,diogomg/olsrd