(Code from @CaMer0n)

App root files introduced in #4099

Format is different and currently incompatible.  The checksum has been
replaced with an associated array where the keys are the e107 version
and the values are the checksum from that e107 version.

Looks like SQLite scales better when there are more files to put in the
database.

Much faster checksumming of deleted files by using git-checkout instead
of git-show

This has two benefits:

1. Protects the SQLite database from being accessed on the Internet by
   having the e107_INIT constant check.
2. Compresses the SQLite database, saving over ⅔ of the space!

Now uses bit flags, as the previous approach of "overriding" the
validation code may hide information.  Previously,
e_file_inspector::VALIDATION_FAIL could be overridden by
e_file_inspector::VALIDATION_OLD.  Now, e_file_inspector::VALIDATED_HASH
and e_file_inspector::VALIDATED_UPTODATE provides information about
both.

- MOD: e_file_inspector::validate() will no longer bother with
       checksumming a file if the database hash is not present for the
       requested version.
- MOD: Better check for e_file_inspector::VALIDATED_DETERMINABLE
- MOD: e_file_inspector::VALIDATED_UPTODATE will now pass if there is no
       checksum in the database and no calculable checksum in the real
       file.
- FIX: Better documentation for
       e_file_inspector_interface::VALIDATED_DETERMINABLE
- FIX: Use the same bit for e_file_inspector::VALIDATED for a full
       validation check in e_file_inspector::validate()

Optimized performance of e_file_inspector_sqlphar::pathToDefaultPath()
by eliminating expensive method calls

PDO SQLite was performing unacceptably poorly.
Let's just load the entire integrity image into RAM…

Squeezed out more performance at the cost of memory usage

e_file_inspector_json_phar is an extended implementation of
e_file_inspector_json that encapsulates a JSON core image into a
gzip-compressed phar.

This results in space savings of over 60% compared to plain JSON.

Now File Inspector detects old files regardless of their hash value.

Now supports:

* "Show Core Files"
* "Show Missing Core Files"
* "Show Non Core Files"
* "Show Old Core Files"

Removed support for:

* "Exclude Language-Files"

Integrity is now always checked.

List mode is supported again

Also added file size support

Bugfixes related to this change:

* e_file_inspector: During validation, the checksum is now calculated,
  even if the file is old.
* e_file_inspector_json: Strip the "v" from the beginning of version
  numbers in the database to make them proper PHP-standardized versions.

Bugs fixed:

* Security failure status is now prioritized in
  file_inspector::getStatusForValidationCode()
* File Inspector list view now supports filters

Low-hanging resolutions for Code Climate