Merge pull request #1 from backbone87/master

Add metapalettes support.
Rework to composer scheme.
Mark version 1.2.0.
Remove version string from composer.json
Update composer.json.
Replace legacy package.
Fix replace of legacy package.
Add missing dependency bit3/contao-meta-palettes.
Do not overwrite $GLOBALS[FE_USER_TEMPLATE].
introduce namespaces
separate DCA helper classes from DCA files and resolve naming conflict
with template_override