Issue #232 Move Welcome Screen into repository and make prettier

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Name: Issue #232 Move Welcome Screen into repository and make prettier
Description: HTML file and css for welcome screen based on wiki text/webpage design
Gist URL:
Cryptography: No
Author(s): Self
I hereby declare that I accept to contribute following the openETCS terms of use and the openETCS IP policy.

http://openetcs.org/termsofuse

https://github.com/openETCS/ecosystem/wiki/IP-Policy

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