Implements Quandl support for Python.
It was not possible to derive from Quandl in order to select the column. If the data did not have "close", it would thrown an exception since it would look for this work in a dictionary.
It is now possible to select the column.
See example QuandFuturesDataAlgorithm.py
This includes updating all usages of symbol as a security identifier to use the new type.
The type includes a unique field, SID, as well as the current ticker's value. This allows
for consistent addressability while also allowing the ticker to evolve over time with the
mapping changes.
Effort was made to maintain compile and runtime backwards compatibility.
Also cleans up IAlgorithm interface of unused/old methods
Slice is a new type that contains all the data from a time slice to be sent into an algorithm
AlexCatarino