- with some `<text>` hacks, generated HTML is almost identical to tag helper version
- attribute order (HTML helpers consistently order alphabetically) is primary difference
- bit more testing, therefore related to #453
nits:
- remove some trailing whitespace
- clean up style in `MvcTagHelperTest[s]` and `MvcTagHelper_HomeController`
- e.g. more init syntax, fewer duplicate variables
- correct "MvcTagHelperTest~~s~~" file / class name
- remove unused `Order.OrderNumber` property in MvcTagHelpersWebSite project
- correct one spelling mistake
