Improve search data file

[pyrog]

1. The files generated by jekyll contain a lot of spaces and empty lines, especially all-translation.json used by the jQuery search script.
   It could be minified with a Jekyll plugin or ruby script run by travis/rake.
2. Also, this file contain titles in all languages but the search script use only the current language.
   So, we could generate a file by language and load only one at a time.
3. Search take care of accentuated char:
   • In french the search editeur return "Edition avancée", "Editer le Wiki OSM"
   • The search éditeur find "Éditer à distance…", "Éditeur iD", "Éditer avec JOSM"

💡 To "fix" this, I suggest to test a plugin with full text search capabilities like jekyll-lunr-js-search

[althio]

Originates from #19 (comment)
Discussed in #150

Need to assess the proposal from @pyrog with

💡 To "fix" this, I suggest to test a plugin with full text search capabilities like jekyll-lunr-js-search

[pyrog]

See #328 to discuss how to use Travis.CI

[Nick-Tallguy]

Closing as stale. A champion willing to work on this is weL come to open it and work on it.