feat(#50): convert to phi and back

[maxonfjvipon]

Closes: #50

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PR-Codex overview

This PR focuses on adding functionality to convert EO programs to φ-calculus expressions and vice versa.

Detailed summary

• Added eo-maven-plugin dependency for conversion
• Four stages of conversion: registration, parsing, optimization, and actual conversion
• Added goals in build pipeline for conversion
• .eo files are converted to .phi files and placed in phiOutputDir directory
• Added goals in build pipeline for converting φ-calculus expressions back to EO
• Result .eo files are placed in printOutputDir directory
• Example of EO Fibonacci program in φ-calculus provided

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[maxonfjvipon]

@yegor256 please have a look

[yegor256]

@maxonfjvipon one small typo. Maybe it's good to add spell checking to our blog, similar to how it's done in my blog: https://github.com/yegor256/blog/blob/master/Rakefile#L185-L233

[maxonfjvipon]

@yegor256 yeah, it would be nice. Please have a look one more time

[yegor256]

@rultor merge

[rultor]

@rultor merge

@yegor256 OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor merge

@yegor256 Done! FYI, the full log is here (took me 3min)