fix long sig printing

[Roger-luo]

• fix long signature printing, now produce a more readable error
• fix problem that -V, --version is missing in the entry doc

[codecov]

Codecov Report

Merging #176 (48de198) into master (e349a8b) will increase coverage by 1.41%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #176      +/-   ##
==========================================
+ Coverage   81.13%   82.55%   +1.41%     
==========================================
  Files          19       19              
  Lines        1272     1278       +6     
==========================================
+ Hits         1032     1055      +23     
+ Misses        240      223      -17     

Impacted Files	Coverage Δ
src/frontend/cast.jl	80.52% <ø> (ø)
src/codegen/julia.jl	86.88% <63.79%> (+0.16%)	⬆️
src/ast/printing.jl	92.54% <100.00%> (+10.90%)	⬆️

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