Infinite loop in flow control + name refactor needed

[SvenT-1643710]

In file src/flow-control/flow.control.ts in function getStreamFrames(...) there is an infinite loop due to ableToSend(...) [from flow.controlled.ts]having to return lessThanOrEqual(temp) instead of lessThan(temp)

ableToSend should probably be refactored to a more clear name

commit hash: 9ee804d
on branch congestionControl