First pass for cleaning loadTable code

The loading function works in 2 steps, infer the attributes of the
table to be loaded (types, sparse vs dense, header), then load it. The
advantage is that the code better organized and both the analysis and
loading steps consume much less RAM.
First pass for cleaning loadTable code

The loading function works in 2 steps, infer the attributes of the
table to be loaded (types, sparse vs dense, header), then load it. The
advantage is that the code better organized and both the analysis and
loading steps consume much less RAM.
Remove useless type_tree Table attribute as it can be optained from {I,O}Table
Improve error message when type is not supported by mutual_information
Add operator<< to stream Table
Fixed a few bugs in the new loading table code
Use the new code (to test it)