Reverse MIB storage format

[gpotter2]

See #1441

This PR reverse the way MIB data is stored in scapy: it makes more sense to use the unique OID as key in the storage dictionaries, rather than its value, that can be a duplicate

I'm pretty sure this even improve speed, as we use self[key] less often.

Warning: This PR has 2 breaking changes

• The format of the data dictionaries (raw) has changed, so direct usages of the dictionaries will fail (unlikely to be used as so: people should use conf.mib)
• The real values are now being used, rather than the formatted ones (as the values were stored as keys). This means that - which was previously converted to _ (I.e sha1-...) will not be replaced anymore. This is the wanted usage, but not the one there used to be. (I’m open to a compatibility “- to _” function if necessary, but I’d rather move away from it)

[codecov-io]

Codecov Report

Merging #1611 into master will decrease coverage by 10.1%.
The diff coverage is 82.6%.

@@             Coverage Diff             @@
##           master    #1611       +/-   ##
===========================================
- Coverage   85.26%   75.16%   -10.11%     
===========================================
  Files         179      125       -54     
  Lines       42143    29489    -12654     
===========================================
- Hits        35935    22164    -13771     
- Misses       6208     7325     +1117

Impacted Files	Coverage Δ
scapy/asn1/mib.py	89.04% <82.6%> (-1.1%)	⬇️
scapy/layers/tls/automaton.py	15.78% <0%> (-64.92%)	⬇️
scapy/sendrecv.py	24.55% <0%> (-58.75%)	⬇️
scapy/arch/bpf/core.py	25.24% <0%> (-54.37%)	⬇️
scapy/arch/common.py	42% <0%> (-52%)	⬇️
scapy/as_resolvers.py	32.71% <0%> (-48.6%)	⬇️
scapy/layers/tls/automaton_cli.py	31.88% <0%> (-45.15%)	⬇️
scapy/layers/tls/automaton_srv.py	26.66% <0%> (-44.71%)	⬇️
scapy/contrib/ppi_geotag.py	47.69% <0%> (-42.31%)	⬇️
scapy/modules/nmap.py	57.46% <0%> (-39.56%)	⬇️
... and 103 more

[guedou]

Looks good to me. Could you add docstrings do the methods that you are modifying? Thanks!

[gpotter2]

Added some vague quite vague docstrings (I'm not 100% sure of each's function exact doings)

[guedou]

@gpotter2 Thanks! This will help us get a better understanding of the code.