This turned into a larger endeavour then intended but now we're using our
own label system on level lines to be able to display things nicely
**pinned wherever we want in the UI**. Keep the old ``LevelLabel`` for
now for the L1 graphics but we'll likely replace this as well since i'm
pretty sure the new label type (which wraps `QGraphicsTextItem`) is more
performant anyway.
For labels that want it add nice arrow paths that point just over the
respective axis. Couple label text offset from the axis line based on
parent 'tickTextOffset' setting. Drop `YSticky` it was not enough
meat to bother with.
The min tick size is the smallest step an instrument can move in value
(think the number of decimals places of precision the value can have).
We start leveraging this in a few places:
- make our internal "symbol" type expose it as part of it's api
so that it can be passed around by UI components
- in y-axis view box scaling, use it to keep the bid/ask spread (L1 UI)
always on screen even in the case where the spread has moved further
out of view then the last clearing price
- allows the EMS to determine dark order live order submission offsets
Async spawn a deats getter task whenever we load a symbol data feed.
Pass these symbol details in the first message delivered by the feed at
open. Move stream loop into a new func.
Basically a stop limit mode where the dirty execution-condition deats
are entirely held client side away from the broker. For now, there's
a static order size setting and a 0.5% limit setting relative to the
trigger price. Swap to using 'd' for dump and 'f' for fill - they're
easier for use with ctrl (which is used now to submit orders directly to
broker - ala "live (order) mode"). Still more kinks to work out with too
fast cancelled orders and alerts but we're getting there.