Support inline date-picker

[buremba]

This is one of the most requested features, here are some references:

ElemeFE#6805
ElemeFE#18175

A few attempts:
kpabi@317c710
ElemeFE#18175

If the intention is to fork Element and implement needed features & fix outstanding bugs, I believe that this would be a great addition.

Thanks for the attempt to maintain the library!

[CarterLi]

I did encounter this issue before, but I worked around it using some tricky hacks.

I'll have a try.

[CarterLi]

After some investigations, I found that the design of date-panel is very strange. It has no properties, all data are set manually in picker.vue using direct value assignment. That makes date-panel very hard to be used independently.

I'd like to rewrite picker.vue with component-is, but I'm very busy these days. Please be patient.

[CarterLi]

PRs are welcome

[buremba]

@CarterLi we also use some nasty css hacks but it's not reliable. I tried to patch the internals in order to make it work but without a write, it's just a workaround as you explained. :/