Fix: removeDotSegments("0") not working (#19315)

Net_URL2 was not able to properly apply the removeDotSegments()
method on a string that consisted only of the single Unicode
Character 'DIGIT ZERO' (U+0030) in US-ASCII (RFC 20) binary
octet encoding.

The issue was reported as Pear Bug #19315 on 2012-03-04 04:18 UTC.

Steps done:

- Add Test 19315
- Fixed Pear Bug #19315 in class Net_Url2 removeDotSegments() method
Dead Code Removal
Whitespace Fixes
Package.xml preparation.
Maintain Pear Coding Standards in class Net_URL2

- According to PHPCS Pear Coding standard
- Fixed typos
- Fixed PHP Code Inspections (PHPStorm)
Removed superfluous data

Removed duplicated array key/value pair.

- Not the first example data anyway (RFC 3986, section 5.4)
Rest of the code using single quotes

Rest of the code used single quotes, but not every rest of the
code. This has been fixed now.

- Single quotes are used in code
- Double quotes are used in comments