Improvements made while working on SCP-Clicker

[TangentFoxy]

• fixed an error with dynamics of creating text element
• added move method to elements
• removed duplicate inspect submodule
• added pop.constants (for now just for use with mouse handling, future TBD)
• made pop.load() able to be called multiple times and used to load additional elements/skins/extensions at any time from anywhere

[TangentFoxy]

I'm making this comment as a separator between further commits and to remind myself to update the description of what has changed on this branch later.

[TangentFoxy]

In all commits to this point, here are the changes:

• Element:align() should always return the element for chaining, it's your fault if you attempt to align something that doesn't have that set (note: I am uncertain I want to keep this thought, it kinda makes sense align should warn you somehow if you call it and it isn't supposed to be)
• text element parameters are properly optional now
• text element can accept non-text data as long as tostring() on it will work
• text:getText() method
• text:setColor() method
• added check to get hovered element, in pop.hovered
• fixed bug in output of printElementTree
• elements update by default
• element:setPosition()
• element:delete()
• element:move() moves children like it was supposed to (whoops!)
• debugDraw stuff moved into pop instead of expecting elements to have that (that was a stupid decision past me)
• debugInfo expected in elements to give additional info besides type (this is a better idea to have as a soft requirement)
• mousereleased events now only activate on drawn elements
• fixed order of event calling (but I'm not sure ultimately whether I broke and then fixed it or fixed it, or both for different parts)
• data.hoverable boolean on elements, defaults to true
• pop.wheelmoved() event handler added
• pre-0.10.0 mousewheel events are handled like post-0.10.0 events

[TangentFoxy]

• element:getPosition() added
• removed duplicate checks in mouse handling
• event handlers now must explicitly return false when they fail to handle an event, instead of explicitly returning a truthy value on success (in other words, an event handler handles an event unless it returns false)