Refactor code in OASIS

[CodeBear801]

Here records refactor suggestions for OASIS:

• Change ChargingStatus -> State feat: Implement function to calcualte charge cost #204 (comment)
• Change name of package solutionformat -> solution feat: implement type to record internal solution #205 (comment)
• Replace floatEquals using the one defined in util feat: Implement function to calcualte charge cost #204 (comment)
• Change interface name ChargeStrategyCreator to a shorter name Refactor code in OASIS #211 (comment)
• Move location to integration/map feat: Implement function to calcualte charge cost #204 (comment)
• Refine the structure of ChargeInfo Refactor code in OASIS #211 (comment)
• Change ChargingCost-> Cost feat: Implement function to calcualte charge cost #204 (comment)
• Change from cost -> weight Change all term of cost to weight in OASIS's code #201
• Refactor State, add member functions not expose internal state fix: refactor code for oasis service, more details please go to #223 #224 (comment)

[CodeBear801]

Suggestions:

#204 (comment)

Already abstract to issue's description.

[CodeBear801]

Suggestions:
#204 (comment)

Already abstract to issue's description.

[CodeBear801]

Suggestions for chargeInfo
Current definition is:

type chargeInfo struct {
	arrivalEnergy float64
	chargeTime    float64
	chargeEnergy  float64
}

• May be should change chargeEnergy to chargestrategy->State, use State to hide information of chargeEnergy, maybe later could add cost.
• ChargeTime could also be recorded in State, but I decide to still keep it in chargeInfo. There might be a situation in the future, user only want to charge his car for certain time, such as 1 hour, he didn't care about how much energy could be charged. So the final status of state still be fixed, just charge duration is pre-calculated by strategy but chargeEnergy is dynamic during evaluation.

[CodeBear801]

Suggestions:
#215 (comment)
Already abstract to issue's description.