borschik freeze: tech to freeze files in dirs
New techs: js-link and json-links
js-links - freeze static imgs in js
json-links - freeze dynamic imgs in js
new tech to freeze files in html
Freezes script@src, img@src, link@href
relative paths in require
relative paths in require
move result to local scope
relative paths in require
unit tests
unit tests
unit tests
unit tests
remove process.env.BORSCHIK_FREEZABLE_EXTS
forgotten js for browser
Revert "forgotten js for browser"

This reverts commit 355f5b2f60fc6756e84233d141d780bf75676f3a.
don't use tech in borschik freeze
rename borschik-freeze
fix paths after rename
Add flexibility to freeze

So I can extend tech with my custom extensions in this way

my-tech.js
```js
isFreezableUrl: function(url) {
  return this.__base(url) || myRe.test(url)
}
```
remove process.env.BORSCHIK_FREEZABLE_EXTS
remove process.env.BORSCHIK_FREEZABLE_EXTS