Dynamic import/merge bootstrap and CLARIN style extensions

[twagoo]

Migrated from Trac #946

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In version 4.0, the bootstrap based CLARIN styles are fully included with the VLO sources. It would be better to do the following build time:

• retrieve (via Maven, see base_style #4) CLARIN's customisations (variables.less and potentially some kind of clarin.less) and put these in the right location
  • separately retrieve (also via Maven?) and extract the bootstrap less sources if not provided via the CLARIN distribution
• include the core bootstrap and CLARIN customisations within the VLO's main ''less'' file and compile the less using a Maven plugin (this already happens in the current development branch)

When this is in place, the copies of the bootstrap sources and CLARIN customisation/override file(s) can be removed from the VLO sources.

[twagoo]

Fixed in 9293640beec392e6ae583ccbe1c81a5d9f224db3, 99c4b613606901d3186f6061ba085bf4a56e696e, 1428f115edfc643af47dd6ffba9a740e42c2a8de, 0c8168e1cb0bd574edff51f3133ba2d224f05a9d