Have the more user-friehdly way to create and edit the time-tag.

[andy840119]

should check if should have those features:

• able to create time-tag in the target of string index.
• able to remove time-tag in the target of string index.
• able to move like recording time-tag caret and remove unneeded time-tags
• able to change the time-tag state (e.g: 5, start -> 4, end)
• able to shift the time-tag (e.g: 5, start -> 6, start)

Also, should think about:

• implement all features on the single page or multi-page?

Origin issue:
#1169

[andy840119]

We need to separate into two parts:

• create
  • create the time-tags
• adjust
  • delete the time-tags -> maybe clear D or Delete
  • shifting the time-tag index or state (maybe press z + <- or -> to change the index, press x + <- or -> to change the state)
  • clear the time(maybe? click R ?)

[andy840119]

Maybe we should create a component to let users able to switch between creating and adjusting mode.

[andy840119]

Great!
This can be the first part of the implementation of this discussion.

[andy840119]

Implemented in the #1218

[andy840119]

Also, seems there are lots of key-related actions is in the main lyric editor class.
Maybe should separate them into several classes.
.
Note:
should only place the common action in the LyricEditor(e.g: move caret action.)

[andy840119]

Implemented in the #1219

[andy840119]

Close this issue because it's not updated and duplicated with #2225 and #2207