cleanup of glCanvasArea.cpp

[nathanfranklin]

There is lots of code repeat that should be cleaned up.

    // Go through all the particles and make a list of
    // known types
    int numberOfParticleTypes = 0;
    for (i=0;i<ad.numberOfParticles;i++) {
        if (this->particleIsInSlice(i)) {
            isInList = FALSE;
            for (int j=0;j<numberOfParticleTypes;j++) {
                if (typeCmp( (char *)&particleTypes[j], (char *)&ad.particles[i].type ) == TRUE) {
                    isInList = TRUE;
                    j = numberOfParticleTypes;
                }
            }
            if (isInList == FALSE) {
                // Found a new particle -- add it to the list
                if (numberOfParticleTypes < MAX_PARTICLE_TYPES) {
                    typeCopy( (char *)&ad.particles[i].type, (char *)&particleTypes[numberOfParticleTypes]);
                    numberOfParticleTypes++;
                }
            }
        }
    }

[nathanfranklin]

This work of finding what particle types exists is repeated in elsewhere (e.g. in setData in lcBoard.cpp)