aligned protocol logic with opensim-git
corrected WebFetchInvDescHandler when folder cannot be requested

a common problem of the HG 2.0 suitcase to trigger all sorts of errors on sims they visit.
The viewers still request the folders when updating the inventory.
changed default of HGInventoryService

the problems alongside HG 2.0 produces are a large nuisance.

The protective capability is pretty low as anyone can implement a mapping service to redirect the inventory service URLs to the unprotected one.
removed OnLook specifics that were missing during compile tests
added complete OnLook stuff (seems there are people with interest for it)
improved HG teleport usability. there is now a more detailed error messaging towards the user when failing due to input error or grid problems.
removed duplicate using line
added exception catch around get_image_assets
integrated opensim-git cfaf904a3b2ab7a8be062d21b2d16cae88a6876e.

LSL key should be implicitly cast to a boolean value

Signed-off-by: ft <ft@noemail>
Merge pull request #5 from ft-/master

Merge in a bunch of updates from the arribasim master