Use gadgets to render some part of ERP5 ui.

Use TabbularGadget API to render initial tab this way we can switch to from it flawlessly as it will be registered into TabbularGadget interla gadget_list structure.

following format defined in system preference level.

so that we will not have HTTP authentication dialog in case of  Unauthorized exception to prevent blocking in functional tests.

Create a sql cache for getInventory call
Remove full-inventory optimisation as it now useless
Implement full-inventory feature directly into stock
Make erp5_pdm depends on this optimisation
Install optimisation for all unit tests

> Note, ImageMagick assumes the sRGB colorspace if the image format does not indicate otherwise.
http://www.imagemagick.org/script/command-line-options.php#colorspace

Also updated expected converted result with sRGB output.

This reverts commit a4072868.
=> it makes test testERP5WebWithDms failing. Please update unit
test and also add test to check what you fixed with this change.

Adjust test accordingly and fix bad test.

> Note, ImageMagick assumes the sRGB colorspace if the image format does not indicate otherwise.
http://www.imagemagick.org/script/command-line-options.php#colorspace

First select pads for current user, then if it's anonymous user and it's preferred so return public knowledge pads for context. This change allows logged in users to have their own customized pads independently from value of a web site preference : "Force Anonymous Gadget " and still we can show or hide public pads for context for anonymous.

In case still we want to show default pads for logged in users we can use preferences which can contain knowledge pads templates. The templates can itself be customized which allows a KM or ERP5 UI site to show a set of default pads for any context which with a single click can be adjusted by user to his needs.