ENH: Allows history to be dynamic and grow the container at runtime.

Previously, all specs had to be pre-allocated by using the 'add_history'
function. This is now no longer required and instead serves as a hint to
the HistoryContainer to pre-allocate the space for the given spec.

History can grow by increasing the length for a frequency, adding a
frequency, or adding a field. It can grow with any combination of
these.

HistoryContainer now is aware of the data_frequency of the algorithm,
and no longer uses the daily_at_midnight flag; instead, this is the
default behavior.
ENH: Adds a closes_in_range and opens_in_range.
DOC: Updates the release notes to include information about the dynamic
history update.
ENH: Changes the default offset for time_rules.market_open to 1, and
makes it an offset from 13:30 UTC.

This is to be more consistent with the market_close, which is an offset
from 20:00 UTC.

This also makes market_open and market_close cache the dt to offset from
for each day.