osc.lua: add osc-tcspace script option

Generally, the hard-coded sizes used for the OSC elements are
comfortable regardless of the font used, but the timecode fields have
relatively many characters, and so are affected to a greater degree by
fonts with a wider or narrower average character width than expected.

This allow users to adjust the space reserved for the timecode fields to
compensate.

player/lua/osc.lua

@@ -43,6 +43,7 @@ local user_opts = {
     tooltipborder = 1,          -- border of tooltip in bottom/topbar
     timetotal = false,          -- display total time instead of remaining time?
     timems = false,             -- display timecodes with milliseconds?
+    tcspace = 100,              -- timecode spacing (compensate font size estimation)
     visibility = "auto",        -- only used at init to set visibility_mode(...)
     boxmaxchars = 80,           -- title crop threshold for box layout
     boxvideo = false,           -- apply osc_param.video_margins to video
@@ -1480,6 +1481,11 @@ function bar_layout(direction)
     local padY = 3
     local buttonW = 27
     local tcW = (state.tc_ms) and 170 or 110
+    if user_opts.tcspace >= 50 and user_opts.tcspace <= 200 then
+        -- adjust our hardcoded font size estimation
+        tcW = tcW * user_opts.tcspace / 100
+    end
+
     local tsW = 90
     local minW = (buttonW + padX)*5 + (tcW + padX)*4 + (tsW + padX)*2