Add support for Simple File Verification

[Alhadis]

Summary

This pull-request adds support for Simple File Verification (.sfv) files, which contain a list of file checksums in CRC-32 format:

; This is a comment
file_one.zip   c45ad668
file_two.zip   7903b8e6
file_three.zip e99a65fb

Description

Unlike the ad-hoc formats added in #5138, SFV uses an explicit (albeit poorly-documented) syntax that supports comments and quoted filenames. Some SFV readers are also picky about whitespace and punctuation separating the filename from the checksum. Some even support multiline comment blocks, which are typically intended for those annoying banners that script-kiddies love stuffing into their WaReZ's .NFO files:

;!SFV_COMMENT_START
 _ _______________             ___   ___  _            _
| |___ /___ /___  | __      __/ _ \ / _ \| |_      ___| |_ ___
| | |_ \ |_ \  / /  \ \ /\ / / | | | | | | __|    / _ \ __/ __|
| |___) |__) |/ /    \ V  V /| |_| | |_| | |_ _  |  __/ || (__
|_|____/____//_/      \_/\_/  \___/ \___/ \__( )  \___|\__\___|
                                             |/
;!SFV_COMMENT_END

These considerations rule out the possibility of using the checksum grammar I wrote for #5138, which was designed to handle freeform text broken up by well-formed checksum lists (like readmes, verification instructions, etc).

Colour rationale

#C9BFED was taken from the CRC-32 checksum of the words "Simple File Verification".

λ printf '%x\n' "`printf 'Simple File Verification' | cksum -o3 | cut -d\  -f1`"
c9bfed14

Checklist:

• I am adding a new language
  • The extension of the language is used in hundreds of repositories:
    ~5,490 results for the .sfv extension (~320 results in Code Search)
  • I have included a real-world usage sample.
    Finding a permissively-licensed example was next to impossible, so I took to generating samples using rhash(1).
  • I have included a syntax highlighting grammar
  • I have updated the heuristics