v0.5.0

• 提高 graph.py 中 binary_tree() 的效率 by @Sweetlemon68 (#80)
• fixes #92 and restructure Vector.py by @bzy-nya (#94)
• Update math.py by @houmy555809 (#98)
• fractions.gcd -> math.gcd (#84)

Full Changelog: 0.4.3...0.5.0