Add ignore_parse_errors option to ComposerRequireChecker

[jyggen]

Q	A
Branch	master
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Documented?	yes
Fixed tickets	-

This adds an option to enable --ignore-parse-errors, which is available in ComposerRequireChecker since 0.2.0.

One thing to note is that the world will crash and burn ComposerRequireChecker will throw a hissy fit if you have <0.2.0 installed and enable this. I think pointing this out in the docs should be good enough since the option is opt-in. We could always go down the route of version detection, but composer-require-checker --version identifies itself as 0.1.1-dev on 0.2.0 :(

[veewee]

Looks good to me. The documentation is clear to me. I would also avoid the version detection.