Implemented 3opt, might still be bugs, only 1.8 points on kattis
Moved functions in graphic.h to graphic.cpp
Added missing 3-opt exchange, show graphics on each step
Merge branch 'master' of github.com:ColacX/tsp_source

Conflicts:
	2_opt.cpp
	graphic.h
	main.cpp
Moved graphic.h functions to graphic.cpp
Added USE_GRAPHICS define in graphic.h

Define it to draw graphics while updating the path
Fixed warnings, signed/unsigned mismatch and float -> int conversion
Changed 2-opt to update everytime an improvement is found, 15.3 points

Also finishes in 0.5s at the most so more tests can be run
Added startTime parameter to opt2 and opt3

Run clock() at the start of main for more accurate timing
Use opt2 -> opt3 -> opt2 to search for a better path, ~22 points
Moved clock() test into the inner loop in opt2/opt3 for reliability