Implement release process

[cburgdorf]

What was wrong?

We didn't have a process to cut releases.

How was it fixed?

1. This adds support for towncrier so we get release notes similar to the Trinity release notes except that they are in markdown for us

Working with towncrier is explained here

2. Cutting releases is a two command process and its explained in more depth here

3. After the make release command Github automatically picks up the release, produces binaries and puts it on the release page.

4. The current version was moved back to 0.0.1 just so that we free up 0.1.0 for the first real release.

[codecov-io]

Codecov Report

Merging #157 (5591f96) into master (931d659) will decrease coverage by 0.84%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #157      +/-   ##
==========================================
- Coverage   82.23%   81.39%   -0.85%     
==========================================
  Files          44       44              
  Lines        3028     3133     +105     
==========================================
+ Hits         2490     2550      +60     
- Misses        538      583      +45     

Impacted Files	Coverage Δ
compiler/src/yul/constructor.rs	53.84% <0.00%> (-9.80%)	⬇️
compiler/src/abi/elements.rs	73.91% <0.00%> (-7.04%)	⬇️
semantics/src/namespace/events.rs	94.44% <0.00%> (-5.56%)	⬇️
semantics/src/namespace/types.rs	56.85% <0.00%> (-5.03%)	⬇️
semantics/src/traversal/expressions.rs	76.16% <0.00%> (-2.76%)	⬇️
semantics/src/traversal/functions.rs	45.28% <0.00%> (-0.44%)	⬇️
semantics/src/errors.rs	5.55% <0.00%> (-0.33%)	⬇️
compiler/src/yul/mod.rs	0.00% <0.00%> (ø)
semantics/src/traversal/contracts.rs	100.00% <0.00%> (ø)
compiler/src/yul/mappers/functions.rs	0.00% <0.00%> (ø)
... and 7 more

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