Added support for Emoji characters to the Typer. Resolves #118.

[awhitford]

Pull Request Process

1. Ensure any install or build dependencies are removed before the end of the layer when doing a build.
2. Update the README.md if needed with details of changes to the interface, this includes new environment variables, exposed ports, useful file locations and container parameters.
3. Increase the version numbers in any examples files and the README.md to the new version that this Pull Request would represent. The versioning scheme we use is SemVer.
4. You may merge the Pull Request in once you have the sign-off of one developer, or if you do not have permission to do that, you may request the second reviewer to merge it for you.

[codecov]

Codecov Report

Merging #120 into master will increase coverage by 0.42%.
The diff coverage is 84.00%.

@@            Coverage Diff             @@
##           master     #120      +/-   ##
==========================================
+ Coverage   68.35%   68.78%   +0.42%     
==========================================
  Files           8        8              
  Lines         689      692       +3     
==========================================
+ Hits          471      476       +5     
+ Misses        218      216       -2     

Impacted Files	Coverage Δ
lib/src/typer.dart	64.47% <84.00%> (+4.19%)	⬆️

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[aagarwal1012]

lgtm