Gas Optimizations

[code423n4]

Visibility declared as public an not used inside the contract can be declared external

Risk: Gas optimization

Findings:

getVotingStage(uint256) should be declared external:
- Gauge.getVotingStage(uint256) (contracts/Gauge.sol#163-171)
Link: https://github.com/code-423n4/2022-05-velodrome/tree/main/contracts/contracts/Gauge.sol#L163-L171

getFee(bool) should be declared external:
- PairFactory.getFee(bool) (contracts/factories/PairFactory.sol#76-78)
Link: https://github.com/code-423n4/2022-05-velodrome/tree/main/contracts/contracts/factories/PairFactory.sol#L76-L78

setGovernor(address) should be declared external:
- Voter.setGovernor(address) (contracts/Voter.sol#82-85)
Link: https://github.com/code-423n4/2022-05-velodrome/tree/main/contracts/contracts/Voter.sol#L82-L85

setEmergencyCouncil(address) should be declared external:
- Voter.setEmergencyCouncil(address) (contracts/Voter.sol#87-90)
Link: https://github.com/code-423n4/2022-05-velodrome/tree/main/contracts/contracts/Voter.sol#L87-L90

whitelist(address) should be declared external:
- Voter.whitelist(address) (contracts/Voter.sol#178-181)
Link: https://github.com/code-423n4/2022-05-velodrome/tree/main/contracts/contracts/Voter.sol#L178-L181

getPastVotes(address,uint256) should be declared external:
- VotingEscrow.getPastVotes(address,uint256) (contracts/VotingEscrow.sol#1184-1199)
Link: https://github.com/code-423n4/2022-05-velodrome/tree/main/contracts/contracts/VotingEscrow.sol#L1184-L1199

delegateBySig(address,uint256,uint256,uint8,bytes32,bytes32) should be declared external:
- VotingEscrow.delegateBySig(address,uint256,uint256,uint8,bytes32,bytes32) (contracts/VotingEscrow.sol#1354-1391)
Link: https://github.com/code-423n4/2022-05-velodrome/tree/main/contracts/contracts/VotingEscrow.sol#L1354-L1391

Recommendation: Change visibility to external
Reference: https://github.com/crytic/slither/wiki/Detector-Documentation#public-function-that-could-be-declared-external

[GalloDaSballo]

The finding will not save gas since 0.6.12