added an extended cuda::load_pointer accepting various load modifiers
added an extended cuda::load_pointer accepting various load modifiers

[git-p4: depot-paths = "//sw/gpgpu/nvbio/main/": change = 17915149]

kimrutherford/nvbio,NVlabs/nvbio,NVlabs/nvbio,NVlabs/nvbio,kimrutherford/nvbio,kimrutherford/nvbio,NVlabs/nvbio,kimrutherford/nvbio