Add implicit conversion from FuturesContract to Symbol

Modified algorithms to use futures contract objects directly instead of accessing their Symbol property.
Removed unnecessary import statements and redundant lines in various files.

Algorithm.Python/BasicTemplateFuturesDailyAlgorithm.py

@@ -12,7 +12,6 @@
 # limitations under the License.
 
 from AlgorithmImports import *
-import QuantConnect.Data.UniverseSelection
 
 ### <summary>
 ### This example demonstrates how to add futures with daily resolution.

Algorithm.Python/ConsolidateRegressionAlgorithm.py

@@ -25,7 +25,7 @@ class ConsolidateRegressionAlgorithm(QCAlgorithm):
         self.set_end_date(2020, 1, 20)
 
         SP500 = Symbol.create(Futures.Indices.SP_500_E_MINI, SecurityType.FUTURE, Market.CME)
-        symbol = list(self.futures_chain(SP500))[0].symbol
+        symbol = list(self.futures_chain(SP500))[0]
         self._future = self.add_future_contract(symbol)
 
         tradable_dates_count = len(list(Time.each_tradeable_day_in_time_zone(self._future.exchange.hours,

Algorithm.Python/FutureOptionChainFullDataRegressionAlgorithm.py

@@ -12,7 +12,6 @@
 # limitations under the License.
 
 from AlgorithmImports import *
-from datetime import timedelta
 
 ### <summary>
 ### Regression algorithm illustrating the usage of the <see cref="QCAlgorithm.OptionChain(Symbol)"/> method

Algorithm.Python/FutureOptionChainsMultipleFullDataRegressionAlgorithm.py

@@ -12,7 +12,6 @@
 # limitations under the License.
 
 from AlgorithmImports import *
-from datetime import timedelta
 
 ### <summary>
 ### Regression algorithm illustrating the usage of the <see cref="QCAlgorithm.OptionChains(IEnumerable{Symbol})"/> method

Algorithm.Python/FuturesChainFullDataRegressionAlgorithm.py

@@ -12,7 +12,6 @@
 # limitations under the License.
 
 from AlgorithmImports import *
-from datetime import timedelta
 
 ### <summary>
 ### Regression algorithm illustrating the usage of the <see cref="QCAlgorithm.FuturesChain(Symbol, bool)"/>

Algorithm.Python/FuturesChainsMultipleFullDataRegressionAlgorithm.py

@@ -12,7 +12,6 @@
 # limitations under the License.
 
 from AlgorithmImports import *
-from datetime import timedelta
 
 ### <summary>
 ### Regression algorithm illustrating the usage of the <see cref="QCAlgorithm.FuturesChains(IEnumerable{Symbol}, bool)"/>