Calculate stream timeout correctly

[timsmid]

This PR improves the way the stream timeout is handled. More specifically:

• The timeout is only set once during the creation of the stream. This is done through the setStreamTimeout method once the stream has been created.
• The unnecessary try-catch block in setStreamTimeout is removed.
• The number_format call for calculating the stream timeout is error-prone. It is replaced with int-casting and a call to round.
• The stream_set_timeout emits a warning when float values are provided instead of ints. This solution ensures only ints are provided. The current solution and PR Fixes #129 Adding optional params to number_format #132 don't fully account for this situation.
• Strange timeout values are denied. This for example includes negative values and values greater than PHP_INT_MAX.