Tdewolff-minify

- cmd: create missing directories for symlinks, see 385
- cmd: preserve file permissions, see 385
- cmd: wait 0.1 seconds before processing watched file change, fixes 372
- cmd: watch now works with file input and output (not just dirs), see 372
- cmd: fix watch functionality for unknown file extension even if --type set, fix watch when src is not a dir; see 372
- cmd: follow symlinks by default, new -p options will copy symlinks without following them, fixes 385
- cmd: use io/fs and demand Go1.16, see 388
- JS: add &&= ||= ??= operators, see 380
- JS: add support for class field definitions, fixes 380
- JS: fix recursion limit in string merging, fixes 382
- CSS: don't remove dimension for zero values inside functions like var and calc, fixes 371
- SVG: don't minify extremely long path data (OSS-Fuzz)
- HTML: keep space after empty `<i></i>`, fixes 390

- JS: fix bugs related to the 'use strict' directive prologues at the beginning of functions and modules, fixes 376
- JS: export statement's function name must remain for non-default declarations, fixes 375
- CSS: prevent quasi-infinite recursion in background's append, from OSSFuzz

- JS: write final ) in ()=>({}), fixes 369
- JS: keep debugger statements, fixes 370
- JS: support ellipsis operator anywhere in arguments, fixes 373
- JS: limit recursion in string merges, from OSSFuzz

- cmd: require `--bundle` for concatenation when the input is a directory, see 348
- CSS: improve performance on background positions (from OSS-Fuzz)
- HTML: don't trim whitespace on all attribute values (in `value` and `placeholder` it's significant), see 351
- HTML: keep value on `translate=no`, see 352
- HTML: support SSI tags, see 353
- HTML: add option `KeepComments` to keep all comments, see 366
- JS: fix endless loop in certain if-else combinations; minify more or/and/conditional expressions that start with a group (from OSS-Fuzz)
- JS: fix import/export with one item, fixes 354
- JS: escape `</script>` in strings, fixes 355
- JS: keep parens in arrow functions for BindingArray and BindingObject, fixes 358
- JS: enclose entire expression in parenthesis if it starts with an object literal, fixes 359
- JS: prevent slowdown for if-else with if in body (from OSS-Fuzz)
- JS: fix errors messages that contain % symbols
- JS: put limits to the number of levels in statements and in expressions (from OSS-Fuzz)
- JS: fix declarations with the same name as in the for initializer, see https://github.com/tdewolff/parse/issues/69
- JS: fix var declarations not adding their usage in all the scopes between its block scope and the function scope
- SVG: keep `width` and `height` attributes on `<svg>`, fixes 367
- XML: keep ampersand and less-than escaped, see 362

- JS: put variable declarations after `"use strict"`, fixes 343
- JS: don't convert hexadecimal representations in strings from `0x80` upwards unless it's UTF-8, fixes 341
- JS: don't merge var declarations after for statement into for initializer, fixes 346
- JS: add parenthesis when necessary to if condition when converting to conditional expression, fixes 347

- Improve error contexts when the file contains unicode characters
- HTML: revert change in v2.9.5 that removed spaces between attributes, fixes 342
- JS: fix bug that converted `(function(){})()` to `!function(){}()` which modifies the return value, fixes 340