Release 2.3.1

• misc: updated codeql ver (2b3bc6b)
• project: updates to structure (f84b816)
• Merge pull request #37 from dosbox-staging/dosbox-staging/cleanup-1 (fcbc330)
• Clarify the peer pointer's validity using an assertion (CWE-476) (a1a909b)
• Avoid pointing to invalid data on scope closure (10be52f)
• Clarify that that the first buffer member is used (82757d0)
• Eliminate an always-true pointer check (d3fa74f)
• Explicitly wrap the host pt into the random seed (608b68e)
• Simplify the freeing of the result list (ac16add)
• Explicitly convert the socket type to an integer (42df534)
• Move the outgoing bandwidth fetch to where its checked (f29dab0)
• Remove the unecessary lower-bound channel limit checks (2af0663)
• Merge pull request #33 from alextwothousand/patch-1 (0bbff4d)
• fix builds again... (32048bb)
• replace add_definitions call with target_compile_definitions (726bb19)
• add include_dir for enet_test (d409d2d)
• Specify link library visibility (e16e91f)
• target-specific compile definitions, fix CI/CD appveyor (bd04c6d)
• use target-based include directories (8abe375)
• CMake <2.8 deprecated fix (61879f5)
• Merge pull request #31 from gamelaster/master (e0e9403)
• Fixed typo + added client example (5a5defa)
• Merge pull request #28 from usernameak/master (a711c9d)
• Merge pull request #30 from nitrix/fix/multiple-definitions (8db7656)
• Marked the IPv6 constants as static to avoid multiple definitions. (908c2e7)
• Parse sin6_scope_id from IPv6 hostname (the %enp3s0 part in link-local addresses) (21c1bac)
• code: don't deprecate internal methods (5bd2ae5)
• code: fix crash caused by improperly initialised callbacks (bc88c7d)