Fix RuntimeError in delete_marker if iid is tk.ALL

[water5]

Fix docs:

• type resolution: float
• type tick_resolution: float

[codecov]

Codecov Report

Merging #92 (a425ef0) into master (1a8ce0c) will not change coverage.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master      #92   +/-   ##
=======================================
  Coverage   89.51%   89.51%           
=======================================
  Files          43       43           
  Lines        4026     4026           
=======================================
  Hits         3604     3604           
  Misses        422      422           

Impacted Files	Coverage Δ
ttkwidgets/timeline.py	78.39% <0.00%> (ø)

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[rdbende]

Fix docs:

type resolution: float
type tick_resolution: float

@water5 You haven't changed anything related to these