getCameraOffsetInitial() call can happen before init()

SL-12994 FIXED [Camera Presets] Zoom fraction should be saved as a part of Camera preset, not as separate setting

'warn-on-failure:no-tabs'

reviewed by Nyx

added some comments and cleaned up code based on review

also, made camera default target and offset live-settable for debugging

reviewed by vir

Function: LLAgentCamera::LLAgentCamera()
File: /indra/newview/llagentcamera.cpp

Function: LLAgentCamera::updateCamera()
File: /indra/newview/llagentcamera.cpp

not a bug, but I cleaned up BOOL->bool

Fix for S32/F32 mismatch.

Took out unnecessary #includes from llagentcamera.*

Orbit/Pan keys were already in llagentcamera.  Pulled alt/walk/left/up/yaw/pitch into llagentcamera.

Lots of superficial cleanup, particularly around "if (" formatting.
Removed LLAgent as a friend of LLAgentCamera and refactored to use accessors.

Removed mAvatarObject / gAgentWearables.mAvatarObject since it's redundant with gAgent.mAvatarObject.

#3 checkin.

Took out llagent "friend llagentcamera" and added accessors instead.
Did some superficial formatting cleanup.

#2 checkin.

Superficial cleanup and some bug fixing (e.g. took out duplicate mDrawDistance from llagent, took out gAgentCameraHACK and gAgentHACK).

First check-in; only compiles, nothing more.