bump sqlite and boost versions (when building libnexa), use curl instead of wget to access files because curl is by default in ubuntu, update one cashlib->libnexa doc, use rostrum latest (daily dev)

This MR adds add two templates that allow people to easily use the python test framework to access mainnet (or testnet). Its is really useful to be able to quickly write a python script to gather info about mainnet/testnet.

These programs aren't tests, so putting them in the rpc-tests directory is not great. However, until we isolate the python code into its own library, "rpc-tests" is the ONLY place this code can be run from, because test_framework must be a subdirectory of the location of these files.

I think its better that they be in rpc-tests, and be available to anyone to use, rather than remain in my personal stash of useful tools.

The current rolling fast filter has a high false negative rate and causes the repeated resending of inv's to nodes that we just received inv's from; By using a generational approach we can avoid this issue caused by erasing data from the filter and so we can use this rolling filter in place of a regular bloom filter and improve overall performance under load significantly.

Still needs a bit of work adding benchmark tests and cleaning up. Probably I should leave the old rolling filter in place so we can see the performance difference in the benchmark tests.