Implement PRIM_ROTATION, PRIM_ROT_LOCAL, PRIM_POSITION and PRIM_POS_LOCAL when manipulating avatars via llSetLinkPrimitiveParams()

Combination of core parts of Freaky's patch at https://github.com/ft-/opensim-patches/blob/master/opensim-llsetlinkprimitive-agent-fix.patch plus further adjustments from myself.
Resolves Mantises 6121, 6421, 6573, 6657
Add some regression tests for previous commit 0e23374
Add Util method to load OpSys env vars
refactor: Make osGetPrimtiveParams() and soSetPrimitiveParams() use common get/set params code in LSL_Api rather than an old copy&pasted section.
minor: remove unused variable from recent commit 0e23374
Stop LSL_Api.GetLinkEntities() from creating an unused list on every parameter except LINK_THIS.  Simplify code.
Add more details to InvalidOperationException logging in SychronousRestFormsRequest.MakeRequest().
refactor: More consistently use using construct within WebUtil to match other existing code there.
Remove long unused UntrustedWebRequest class

This purports to check web requests but doesn't appear to actually do that.
Set up a StreamReader and call ReadToEnd() instead of using the GetStreamString() extension method

This eliminates some stream seeking that was never necessary and makes disposable of the StreamReader consistent with other code
Maybe slightly reduce warp3d memory leakage by disposing of decoded bitmap in Warp3DImageModule.GetTexture()

However, this still appears to be leaking massively, at least for me.  Possible cause is warp3D using GDI objects internally and not disposing of them.
When positioning agent with PRIM_ROTATION in llSetLinkPrimitiveParams(), set the global rotation rather than the local rotation

Functionally the same as the patch in http://opensimulator.org/mantis/view.php?id=7044, thanks Aleric.
This commit also extends the regression test
If an avatar is sitting, send out position updates to clients for any change, not just those outside the usual tolerances.

This is to allow small adjustments of less than 0.05m in functions such as llSetPrimitiveLinkParams() to work
This is another fix for http://opensimulator.org/mantis/view.php?id=7044
Extends regression test for this case.
Don't request a terse update after local teleport - this will be done by the main frame loop anyway and has the potential to race that thread.
Add UUID and ready status (whether region has finished starting up) to "show regions" console output.
Prevent adding a land object if it overlaps any existing objects that have not had their bitmaps adjusted.

This is to prevent an immediate problem in http://opensimulator.org/mantis/view.php?id=7035 where a development code bug occasionally overlays all the existing parcels with a blank parcel owned by the estate manager and to gather more data.
My guess is that this parcel is being created by the new code in LandManagementModule.GetLandObject(), probably some race between threads since this only happens occasionally.
Adds regression tests for this case and for parcel subdivide.
minor: Increase size of parcel name field in "land show" console command output.  Construct table using CDT rather than string formats
Remove array initialize calls in LMM - these are unnecessary as the VM already does this.
minor: slightly simplify code in LandObject.ContainsPoint()
refactor: Simplify land object by using c# get/set auto-properties where applicable.