request to sign message

[tarmo888]

• adds possibility for user to request other chat user to sign a text/object with 2 clicks, just like chat bots can request it from user.

Following features are also in separate PR #592:

• makes it possible to copy the signed message from sign message modal view.
• formats root level of JSON as an unordered list on sign message and signed message modal views, if JSON is nested then shows nested object values like it was showing them before.
• Request to sign chat message will not show JSON white-space in links anymore (it was difficult to click it and took whole screen room).
• Message signed by chat message is now clickable, so the user can see the details in more user friendlier signed message modal view.
• removed using dynamic="" because it will be removed some day by other PR.