make test backward compatible to old PHP versions

initialize log level early

The default log level needs to be initialized before everthing else,
otherwise an error during the option parsing (eg. when an unknown option
is passed) will result in an unessecary stack trace.

honor NO_COLOR environment variable

As argued for on https://no-color.org/

Fix log level setting. closes splitbrain#33

Allow dynamic log level setting

This was inspired by splitbrain#32 but I am not sure this actually the way to go.
Thinking a bit more about the intial post, an even better way would be
to add config file reading to the Options class. Maybe from a .env file?

Merge pull request splitbrain#29 from dwschultz/color-stream-fix

fixes colors on streams other than stdout

do not explicitly call exit(0). fixes splitbrain#21

A normally exiting PHP script will exit with error code 0 by default, so
we don't need to explicitly call it in run()

introduce a more compact help screen

This is inspired by splitbrain#9 but implements it in a more elegant way,
requiring less conditionals.

Merge pull request splitbrain#16 from usox/php74-compat

Ensure php7.4 compatibility

Merge pull request splitbrain#14 from treehousetim/patch-1

Add an accessor function to options for bin