We should move all module folders to new "modules" subfolder

Currently we have all module folders located in top folder. In case, when multiple modules are used, then it's not obvious to user, when folder belongs to module and what folder is system. Also during search for unit configs we also don't know it and scan all folders. This raises a problem in case if site has it's backup under main installation folder.

I propose we create new folder on top level names modules or extensions or something like that and move all current modules there. After moving folder structure will be like this:

/admin
/core
/modules
/modules/in-auction
/modules/in-bulletin
/modules/in-commerce
/modules/in-link
/modules/in-news
/modules/custom
/system
/themes
/tools

Then we scan only "core" and "modules" folder for possible unit configs and installator only will search for modules inside "modules" subfolder. For upgrade we will scan for "core" folder too, because it contains upgrade scripts for In-Portal main module.

As of existing users, who have old folder structure we will post a upgrade notice, that following folders (list of all possible modules) should be moved to "modules" subfolder before performing upgrade.