Version working with more than 5 chips

[NoHomey]

Changes:

C++ changes like const& type of the arguments in the methods and destructor _~AdafruitTLC5947() added .

The call to calloc() is correct now.

_BLANK_ signal control added if is passed to the constructor as _const uint8t& b.

c type changed to _int16t so more than 5 chips can be manipulated.

If merge is made I will add comments (comments only make a good writen code ugly in my opinion).

:)

[ladyada]

sorry for delay, didnt see this PR before... but we ran across the limit of 5 and added support!