Hide globalconf.L

Everything that needs the lua_State should create a local variable like this:

  lua_State *L = globalconf_get_lua_State();

This ensures that the compiler warns if there are two variables with name "L" in
scope. The idea here is that it should become harder to accidentally use the
global lua state instead of the state of the current state.

While writing this commit, I found another place that gets its wrong: Reading
client.focus from a coroutine was broken, since it was returning the result on
the main thread instead of the current one.

Signed-off-by: Uli Schlachter <psychon@znc.in>
timer: Move from C to lua as gears.timer

No API-change (besides the obvious no-longer-a-global-object) intended.

Signed-off-by: Uli Schlachter <psychon@znc.in>
textclock: Round timeout so that displayed time is more accurate

Signed-off-by: Uli Schlachter <psychon@znc.in>
client: Include c.name in the result of tostring(c)

Signed-off-by: Uli Schlachter <psychon@znc.in>