Undeprecate frequently used components

[qstokkink]

Many components in IPv8 are so frequently used, it makes no sense that they are in a deprecated folder. Specifically we should perform the following refactorings;

• [x] ipv8/deprecated/bloomfilter.py ➡️ ipv8/messaging/bloomfilter.py
• [x] ipv8/deprecated/community.py ➡️ ipv8/community.py
• [x] ipv8/deprecated/lazy_community.py ➡️ ipv8/lazy_community.py
• [x] ipv8/deprecated/network_stats.py ➡️ ipv8/messaging/interfaces/network_stats.py
• [x] ipv8/deprecated/payload.py ➡️ ipv8/messaging/payload.py
• [x] ipv8/deprecated/payload_headers.py ➡️ ipv8/messaging/payload_headers.py
• [x] ipv8/peerdiscovery/deprecated/discovery.py ➡️ ipv8/peerdiscovery/community.py
• [x] ipv8/peerdiscovery/deprecated/discovery_payload.py ➡️ ipv8/peerdiscovery/payload.py

Note 1: I do believe the files in ipv8/messaging/deprecated should no longer be used. Note 2: We will have to change the Tribler+Gumby downstream as well. Note 3: We will also have to update the documentation.

[qstokkink]

DiscoveryCommunity addressed in #357.