Problem: :TOhtml doesn't properly handle virtual text when it has
multiple highlight groups. It also improperly calculates position offset
for multi-byte virt_text characters.
Solution: Apply the `vim.api.nvim_strwidth` broadly to properly
calculate character offset, and handle the cases where the `hl` argument
can be a table of multiple hl groups.
- Added `@inlinedoc` so single use Lua types can be inlined into the
functions docs. E.g.
```lua
--- @class myopts
--- @inlinedoc
---
--- Documentation for some field
--- @field somefield integer
--- @param opts myOpts
function foo(opts)
end
```
Will be rendered as
```
foo(opts)
Parameters:
- {opts} (table) Object with the fields:
- somefield (integer) Documentation
for some field
```
- Marked many classes with with `@nodoc` or `(private)`.
We can eventually introduce these when we want to.
