Tdewolff-minify

- When minifying floating points, remove trailing zeros and not other numbers
- Make `M` concurrent-safe
- HTML: keep double quotes around XML-flavour RDFa attributes
- CSS: revert the use of the `RRGGBBAA` format as proposed in Color Module Level 4 as it is not yet an official W3C recommendation
- CSS: `background-position` (also within `background`) now works with 3 and 4 values as well
- SVG: skipping `metadata` or `rect` tags properly even if they are closed by a void tag (like `<rect/>`)
- SVG pathdata: when cursor doesn't move, don't emit any commands

I'm suspecting that `go mod` gets confused from a previously reverted `v2.3.7` release, so just in case this is a new release that will hopefully fix:


$ go get -u github.com/tdewolff/minify/v2

Add Go modules support by using the `github.com/tdewolff/minify/v2` import path.

WARNING: this release may give errors for `go mod` probably due to (local) caching...

**Important: default mimetype for JavaScript is now `application/javascript` (it used to be `text/javascript`).**

- HTML bugfix: keep empty `value` attribute on `<input type="radio">`, because the default is not an empty string
- HTML bugfix: prevent IE conditional comments from panicking in some instances
- CSS: handle `local()` for URLs
- CSS: support `rgb()` and `hsl()` with spaces instead of commas
- CSS: improve minification for `font`, `background`, `background-position`, `background-repeat`, `background-size`, `outline` and `border` declarations
- CSS: reintroduce support for IE star-declaration hack
- CSS bugfix: `margin` and `padding` now check if values that are functions (such as `calc()`) are equal and thus eligible for collapsing
- CSS bugfix: parse bad declarations better
- CSS bugfix: add space for attribute selector case insensitivity between the value and `i` as in `input[type="radio" i]`
- CSS bugfix: do not collapse `outline` to `0` but to `none`
- CSS bugfix: opacity for `rgba()` and `hsla()` in CSS2 cannot be rewritten as `rrggbbaa`
- SVG bugfix: only use the first pair of coordinates for `M` to move back to when encountering `Z`

- CLI: Add bash completion for the `minify` command
- CLI: improved error messages
- CLI bugfix: don't open all files at once when concatenating, which usually panics when >10000 files are open
- CLI bugfix: don't minify modified files twice when watching them
- Bugfix: prevent panic on long decimals with negative exponent, where rewriting would previously cause longer numbers
- HTML: accept alternative syntax for MS conditional comments
- HTML bugfix: `draggable` is not a boolean
- HTML bugfix: do not assume mediatype in `<meta content="x">`
- CSS: add option for CSS2 numbers without exponents
- CSS: trim space in `url()`
- CSS: minify `box-shadow`, `background` and `import` better
- CSS bugfix: prevent panic for functions with no arguments or end parenthesis
- CSS bugfix: keep dimensions for zeros in `flex` property
- CSS bugfix: keep other values for `outline` and `border` when width is zero
- CSS bugfix: font `normal` now handled
- CSS bugfix: add quotes to unquotes `url()` when we can remove the `url` function
- CSS bugfix: only omit number dimensions for <length> and <angle>
- JS bugfix: ASI behaviour for template literals
- JS bugfix: replace comment as space when comment is removed
- JS bugfix: divide by regular expression
- SVG: don't remove empty groups anymore, as CSS or JS might rely on them
- SVG bugfix: prevent panic on invalid pathdata for arcs

This release fixes a number of out-of-bounds panics that could arise in HTML, XML and JS sources. It also allows HTML sources to contain the NULL byte.