wtf 0.3.0

wtf opens to a start screen and works from a menu on Space. A picker finds signals and decodes
the interfaces wtf found in the trace, and :records opens a table that sorts, groups and
filters. An agent working on a trace shows in every window on it, step by step.

Breaking:

• Enter folds groups, buses, streams and composite rows, as Space is now the leader key. A click
  on the fold marker still folds.
• wtf --attach is gone. Open the trace with wtf <trace>: an agent working on it joins the
  window, and :follow follows it.
• :protocol, a session's [[protocol]] and the workspace tool's protocols take roles and no
  clock. The clock goes on the decode: :decode req hs clock=clk valid=req_valid.
• :records opens the records table. A where that keeps no records is no longer an error; the
  table says none match.
• The decode answers of command list the results, then the violations, then the streams they
  are made from.

New:

• A start screen when wtf opens without a trace, with the recent traces and the agents on this
  machine. A trace without a session opens to where to start and the interfaces wtf found.
• Space opens a menu of commands in groups, and which-key shows what can follow a key.
  [keys] and [leader] in the config move them.
• One picker (Space f) for signals, marks, records, commands, sessions, the agent's trail and
  the interfaces found, with a preview. Tab marks several signals, Ctrl-s changes the source.
• Space d d decodes one of the interfaces wtf found, and Space d D starts a :decode line.
• The records table: s sorts, = groups by the sorted field, / filters, Tab goes to the
  next set and Enter jumps to a record. records takes a decode name, a glob or several names.
• The command line completes every command's arguments and shows short docs in a card.
• Notifications fade out, and :messages lists them again.
• A new look: cards, Nerd Font icons (--glyphs nerd), a status line in segments, Name and
  Value headers, a value column of stable width and marks as tabs on the ruler.
• Marks have a name and a note (:cursor 2 60ns name=late note=...), and undo covers marks.
• An agent's queries and changes are a trail in the user's window (:trail). When no window is
  open, present keeps the evidence for the next one opened on the trace.
• A site with a quick start, recipes and every key: https://xtrollyj00.github.io/wtf

Fixed:

• :group on rows inside a group moves them out into the new group.
• zoom given two times points to fit.
• A record's field that really is z draws; only the time between records is blank (#28).
• Computed signals nothing uses are dropped, and present replaces the window's decodes.
• The signal panel keeps its place when computed signals are added (#35).
• A session from a newer wtf changes nothing.
• An agent's message never replaces the user's own on the status line.