sort devDependencies

rename to compile_options.sourcemap

file src/compiler/utils/string_with_map.ts
* indent with tabs
* run prettier
* remove extra whitespace
* add newline at end of file
* wrap long lines
* rephrase some comments

move string_with_map.ts to string_with_sourcemap.ts
rename GeneratedStringWithMap to StringWithSourcemap
rename offset_source_location to sourcemap_add_offset
rename source_maps to sourcemap_list
rename source_locator to get_location
rename as_sourcemap to get_sourcemap
rename encode to sourcemap_encode
move { brace to line before
add some comments

rename decode to sourcemap_decode

allow self-closing <style/>

move fn replace_async back to old place to reduce line diffs
fn preprocess: allow empty argument `preprocessor` (noop)
make fns replace_async, get_replacement pure fns
  pass filename, get_location as argument
restore old format to reduce line diffs
remove empty fields of sourcemap: file, sourcesContent

use _config.js, indent with tabs, rename variables,