v2.4.1 deprecation fix and crawl-delay with "0" value

• fixed deprecation warning "PHP Deprecated: usort(): Returning bool from comparison function is deprecated", see #61
• added php 7.4 to travis CI (all tests are passed), see #62
• return rule for directive "Crawl-Delay" with "0" value, test case is added, see #62
• test file CrawlDelay.php renamed to proper CrawlDelayTest.php, see #62

v2.4.0

• never fail on regexp with compilation failed error when run isUrlAllow from RobotsTxtValidator
• fix travisCI

v2.3.0

• added composer.json file (needs for packagist.org)
• move all code to src/RobotsTxtParser folder
• move tests to tests/RobotsTxtParser folder
• fix code style to PSR compatible format
• improve RobotsTxtValidator (getRelativeUrl function)

v2.2

Fixed parsing error when the latest allow/disallow directive in the block is empty and the next directive is User-agent.

User-agent: *
Disallow:

User-agent: Linguee
Disallow: /api/showcase

URL "/api/showcase" should be assigned (as Disallow) only to User-agent Linguee, not any.

See PR #54 for more information.

v2.1

Release notes:

1. use only English language for README.md (#45)
2. added more phpunit tests for RobotsTxtParser, RobotsTxtValidator (#44, #49)
3. fixed bug in RobotsTxtParser with processing of list of user-agents (#47)
   For example:

User-Agent: ahrefs
User-Agent: SurdotlyBot
Disallow: /

Now will be disallowed path "/" for both user-agents (earlier Disallow: / has been applied only for the latest agent SurdotlyBot)
4. fixed bug with handle character '+' in allow,disallow directives in RobotsTxtValidator (#50)

v2.0 Significantly improve performance of RobotsTxtParser

Main note: refactoring of RobotxTxtParser class to significantly improve performance of parsing a large robots.txt files (100-1000 times) due to improvement of an algorithm of parsing.

• refactored RobotxTxtParser
• save full backward compatibility with previous version
• all phpunit tests passed

v1.0

class RobotsTxtParser
class RobotsTxtValidator.

all tests passed.

Allowed Directives:

• noindex
• allow
• disallow
• host
• sitemap
• user-agent
• crawl-delay
• clean-param