change PF resampling function to match with the book

[goktug97]

• changed resampling function so that it chooses random number once for the starting point.
• condition check is moved from the inside of the resampling function
  to the outside of the function, this way the purpose of the
  function is much clear. Instead "resampling" every iteration,
  resample if the condition holds.

[coveralls]

Pull Request Test Coverage Report for Build 1057

• 14 of 14 (100.0%) changed or added relevant lines in 1 file are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.01%) to 90.341%

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Files with Coverage Reduction	New Missed Lines	%
PathPlanning/ClosedLoopRRTStar/pure_pursuit.py	1	95.35%
PathPlanning/BatchInformedRRTStar/batch_informed_rrtstar.py	5	81.41%

Totals
Change from base Build 1051:	-0.01%
Covered Lines:	6734
Relevant Lines:	7454

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💛 - Coveralls

[AtsushiSakai]

@goktug97 Thank you so much again!!. You are totally right. your code looks better. I will merge it.