added more generic copy constructors allowing to do basic pointer conversions
added more generic copy constructors allowing to do basic pointer conversions

[git-p4: depot-paths = "//sw/gpgpu/nvbio/main/": change = 18442519]

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