* support passing in dictionary as theme definition
Allows setting up lualine with a theme dictionary like:
```lua
setup{
theme = { normal = {...}; insert = { ... }; }
}
```
this was the original behaviour before 37a3b8cc.
* comment
* Enhance Theme
- loaded theme table is nolonger stored in configs and thus not passed
to components. Insted it's cached in highlights.lua
- Reintroducing clear_highlights turns out themes can still change if
setup is called more than once
* Add error messege for invalid theme
It stops lualine from crashing in such incedent
* Apply lua-format
* Small tweeks
* Refactor highlight restoring after ColorScheme
Previously custom highlights/ component highlights had to call
expand_set_theme to make them restored . That's unintuative . Now any
highlight created by lualine.highlight.highlight() will be restored :)
* Renamed component -> var_name | Proper BugFix
John Sun
Shadman
hoob3rt
Hubert Pelczarski
JayceFayne