fromSignature: cache typeOf result.
fromSignature: cache typeOf result.

Change-Id: I513fa9f13bef1c082c75172c4b5ceac11549fed1
Reviewed-on: http://gerrit.aldebaran.lan:8080/16304
Reviewed-by: cgestes <ddb78fe00abb42f91254c16a0860e38eb0781789@aldebaran-robotics.com>
Reviewed-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>
Tested-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>

bsautron/libqi,aldebaran/libqi,vbarbaresi/libqi,aldebaran/libqi,aldebaran/libqi