Dolly camera post-mortem review

[sprunk]

Mostly for the Lua API.

• RunDollyCamera should probably accept the runtime in seconds (not milli)
• PauseDollyCamera should have a "pause now" argument, perhaps if you pass nil. I assume that's what the current default value of -1 does, if so then just document that in the luadoc.
• PauseDollyCamera should probably do something about values outside of the 0-1 range. Clamp or reject
• SetDollyCamera[Look]Curve should have their args documented. What they mean and what format they are in
• SetDollyCamera[Relative]Mode shouldn't accept magic values 1 and 2. Split it into functions, perhaps make the other existing functions also set mode
• SetDollyCameraLookPosition should accept floats in addition to ints
• make SetDollyCameraLookUnit give feedback if given unit is not currently visible (perhaps because it does not exist). Return a bool or something
• make sure SetDollyCameraLookUnit obeys LoS rules, i.e. stop tracking if the unit goes into fog of war
• check Maybe fix #1756 #1757.

[sprunk]

cc @loveridge