Add support to new calculation endpoints.

examples/rest/extra_calcs.py

@@ -0,0 +1,24 @@
+# python -c "from examples.rest.extra_calcs import *"
+
+from bfxapi.client import Client, Constants
+
+bfx = Client(
+    REST_HOST=Constants.REST_HOST
+)
+
+t_symbol_response = bfx.rest.public.get_trading_market_average_price(
+    symbol="tBTCUSD",
+    amount=-100,
+    price_limit="20000.5"
+)
+
+print(t_symbol_response)
+
+f_symbol_response = bfx.rest.public.get_funding_market_average_price(
+    symbol="fUSD",
+    amount=100,
+    period=2,
+    rate_limit="0.00015"
+)
+
+print(f_symbol_response)