Improved lume.distance()'s performance on non-JIT

Replaced use of the exponent operator with multiplications, yielding a
performance increase on non-JIT Lua:

[5000000 calls, Lua 5.1]
old func: 2.03 seconds
new func: 1.17 seconds

[5000000 calls, Lua 5.2]
old func: 1.60 seconds
new func: 0.89 seconds

[2000000000 calls, LuaJIT 2.0.2]
old func: 0.89 seconds
new func: 0.89 seconds
Added better tests for lume.distance()
Improved lume.clamp()'s performance on non-JIT

Removed use of the functions math.max() and math.min() and replaced them
with and/ors:

[5000000 calls, Lua5.2]
old func: 1.37 seconds
new func: 0.53 seconds
Fixed module's table not updating in lume.hotswap()

Changed the returned values from pcall() in lume.hotswap() to be handled
correctly -- the second return value being the wrapped-function's first
return value. This bug would effect hotswapped modules which used the
modern approach of returning a table rather than creating globals.