Unexport thin wrapper functions around libuv?

[jiahao]

The functions

• start_timer
• stop_timer
• start_reading
• stop_reading
• start_watching

are essentially thin wrappers around libuv functions of similar names and probably should be unexported.

1. The last three have no documentation.
2. The counterpart to start_watching, stop_watching, is unexported.
3. start_timer is only called by sleep and timedwait.
4. stop_timer is only called by timedwait.
5. Neither start_timer nor stop_timer validate their arguments, leading to possible weird errors like in start_timer: Saturate arguments to be at least zero #10847

[JeffBezanson]

Yes please. See #1925

[tkelman]

+1, not worth exporting these

Some data points (not a hugely comprehensive sample, just what I happen to have installed):
Tk and ImageView use start_timer
ImageView uses stop_timer
JSON uses start_reading

[jiahao]

Closed by #10885