Implemented PHPStan + Propel2 beta2

[davyrolink]

I firstly implemented PHPStan, then upgraded Propel2 to beta2, fixed a few bugs along the way.

This merge will also resolve: #23 #19 #22

I've only upgraded the 5.0 branch. The differences between the 5.0 and the 6.0 branch seem small, so it shouldn't be too hard to merge into 6.0 and resolve the conflicts (that will resolve #24).
Manually tested with Symfony 4.4 and 5.4
PHP dependency is now 7.4+ (just like Propel2 beta2)

[SkyFoxvn]

tnx for the help i will need time to review it.
But i think it will be better to merge this to branch 6.0 and keep the 5.0 as it it(except bug fixes) so we can have branch working on older PHP versions like 7.2 - 8.0 and another(6.0) working with the new PHP versions like here from 7.4+

[davyrolink]

I'm not sure if supporting PHP 7.2 and 7.3 should be a thing, because they are both end-of-life for quite some time. Symfony 4.4 on the other hand has support for another year, and Symfony 5.4 is supported for the next 3 years, so I feel that supporting those makes a lot of sense.

With that in mind, maybe it could be an idea to continue the 5.0.X versions with PHP 7.2 support, if that is really desired for this bundle, just for bug fixes. Besides that there could be an introduction of 5.1.X versions with PHP 7.4 support, since that is the only way to keep using the latest Propel2 releases.

[SkyFoxvn]

"I'm not sure if supporting PHP 7.2 and 7.3 should be a thing, because they are both end-of-life for quite some time. Symfony 4.4 on the other hand has support for another year, and Symfony 5.4 is supported for the next 3 years, so I feel that supporting those makes a lot of sense."
you are right i didnt have much time to spend on this and think it but the idea its to keep working versions for ppl which cant update the PHP version which im also not sure its make very much sense those days :)

"With that in mind, maybe it could be an idea to continue the 5.0.X versions with PHP 7.2 support, if that is really desired for this bundle, just for bug fixes. Besides that there could be an introduction of 5.1.X versions with PHP 7.4 support, since that is the only way to keep using the latest Propel2 releases."
I dont really desire anything just try to keep bundle working with the little time i have and im open for suggestions.
I like the idea for 5.1.X which support PHP 7.4+ i will make new branch so you can make pull request to new branch 5.1 insteed of 5.0 if you are ok with it.

[davyrolink]

Sounds good to me