[FR]More default commands and more convenient input

[YanCore]

1. Provide more default commands, such as text, H1~H5, bullet lists, and numbered lists.
2. Provide a todo list command to create simple todo lists, and it would be great. And retain the task command.

3. More convenient input. I have enabled "only on new line" because using "/" commands in the middle of a sentence can cause confusion. However, I still hope to be able to switch between commands when no other content has been entered. For example, if I type /h1 and press Enter without adding anything else, I should be able to switch back to normal text by typing /text, or switch to an unordered list with /bulletlist.

I hope "slash commander" can be used conveniently! Commands should be ready to use out of the box to meet most needs, while also supporting the addition of custom commands (with alias and multilingual support).

Incidentally, the MAKE.md plugin includes too many features, and its "slash commander" commands are worth referencing – it provides rich out-of-the-box commands, but cannot remove default commands or add custom ones.