Adds set_density()
Fixes one instance of a duplicate density assignment on an object.
Comments two hacky usages of density which will have to forgo using the setter for now.
Lets us append code to the event of density changing.
Pretty sure this is leading up to some multitile object thing -Lemon
Converts most spans into span procs. Mostly used regex for this and sorted out any compile time errors afterwards so there could be some bugs.
Was initially going to do defines, but ninja said to make it into a proc, and if there's any overhead, they can easily be changed to defines.
Makes it easier to control the formatting and prevents typos when creating spans as it'll runtime if you misspell instead of silently failing.
Reduces the code you need to write when writing spans, as you don't need to close the span as that's automatically handled by the proc.
(Note from Lemon: This should be converted to defines once we update the minimum version to 514. Didn't do it now because byond pain and such)
