Bug fix in Hydrax modules.

I am finded a bug in hydrax`s source files SimpleGrid.cpp, RadialGrid.cpp, ProjectedGrid.cpp.
My application falling down when i trying remove water surface and recreate it with another params. Fail detected in
SimpleGrid.cpp Lines 217-225 (old version)

Module::remove();
if (mVertices)
{
if (getNormalMode() == MaterialManager::NM_VERTEX)
{
delete [] static_cast<Mesh::POS_NORM_VERTEX*>(mVertices);
}
else if (getNormalMode() == MaterialManager::NM_RTT)
{
delete [] static_cast<Mesh::POS_VERTEX*>(mVertices);
}
}
if (mVerticesChoppyBuffer)
{
delete [] mVerticesChoppyBuffer;
}

so, i am modifed that and problem was solved

if (mVertices)
{
if (getNormalMode() == MaterialManager::NM_VERTEX)
{
delete [] static_cast<Mesh::POS_NORM_VERTEX*>(mVertices);
mVertices = 0;
}
else if (getNormalMode() == MaterialManager::NM_RTT)
{
delete [] static_cast<Mesh::POS_VERTEX*>(mVertices);
mVertices = 0;
}

}

if (mVerticesChoppyBuffer)
{
delete [] mVerticesChoppyBuffer;
mVerticesChoppyBuffer = 0;

}

In other modules same code was added.