We implement it for tensor and sparse Contant Variable. This get also done for gpu variable as it inherit from the tensor Constant variable.

- print the number of module with X number of different key.
- print the module whose key.pkl file take more then 1M.

Minor stuff (PEP8 and typos mostly)

Mixed

Cleanup of sparse/basic.py

Fix defaults

fixed debugging and warning messages (grammar and semantics) for cudandarray

previously, it stored the initial value of shared variables in defaults
this wasted a lot of memory
now it does not