Implement extrafields : calendar on date type and new separator type
New method to CommonObject to display extrafields data output
Try for product
New option (MAIN_EXTRAFIELDS_USE_TWO_COLUMS) to split extrafields display into 2 columns
For thirdparty use new method to display extrafield values
Fix : in extrafield force output for date selector
Unique function to show input or output of extrafields datas
Use new function to show extrafields on products
Uniformize usage of extrafields methods
Merge branch 'develop' of git://github.com/Dolibarr/dolibarr.git into extrafields

Conflicts:
	htdocs/comm/propal.php
Merge pull request #793 from jfefe/extrafields

Task #784 : display calendar into data type extrafields / new methods to manage extrafields