Minor code style improvements.

Minor improvements in the project documentation.

Merge pull request kkomelin#46 from taoufiqaitali/patch-1

Fixed `PHP Error: Class 'Str' not found` error for some Laravel configurations

Modified TravisCi config.

Explicitly set default value for allow-newlines config variable to ha…

…ndle cases when this variable doesn't yet exist in the config. (refs kkomelin#41)

Added support for multiple white spaces between parentheses and quote…

…s in a translation function call.

Updated PHP dependency rules to support all future Laravel 6 sub-vers…

…ions by default

Added support for Laravel 6.3 and 6.4. (refs kkomelin#35)

Added Laravel 6.2.x support (refs kkomelin#34).

Merge pull request kkomelin#30 from awardis/laravel-6

Added Laravel 6 support