Cancelling rounds after finalizing will lead to incorrect globalTokenAllocPerIDORound tracking

Description

Rounds may be claimed after finalized, in which each claim reduces globalTokenAllocPerIDORound[idoConfig.idoToken]. When rounds are canceled and were enabled, globalTokenAllocPerIDORound[idoConfig.idoToken] is reduced by idoConfig.idoSize.

Thus, it's possible for the globalTokenAllocPerIDORound to be reduced by more than idoConfig.idoSize per round in case it is finalized and canceled. This means that other rounds could not be claimed as globalTokenAllocPerIDORound would underflow as it had been reduced too much and it may not be possible to cancel them as it may underflow.

Recommendation

According to specs, rounds should be allowed to be canceled after finalized, so globalTokenAllocPerIDORound[idoConfig.idoToken] must be reduced by the amount left of idoTokens that were not claimed. A new variable needs to be created to track the amount of tokens that were claimed per round, such that on cancel after finalizing, globalTokenAllocPerIDORound can be decreased by globalTokenAllocPerIDORound.idoTokensSold - idoRoundConfigs[idoRoundId].idoTokensClaimed.

Additionally, users should not be able to participate or claim if a round was canceled.