Reverted back change from `assert: x equals: y` to assert: (x = u). Actually, even Smalltalk/X SUnit has assert:equals:

Portability fix: do not use Behaviour>>methods. On Smalltalk/X it returns a category reader (in order to be able to read Dolphin fileouts): * use`class methodsDo:` instead of `class methods do:` * use `class methodDictionary size` instead of `class methods size`

Fixed PPCCompiler: must refetch class afer updating instance variables of a given class. The reason is, that in (at least) Smalltalk/X modyfing a layout of a class results in creating a new class rather than updating an old one and migrating instances, i.e., the old class is not identical with the new class. Therefore, to install methods in in correct class, we have to refetch new version from system dictionary. On Pharo it should not harm

Fix in PPCMethod>>addVariable: make sure variable is added only once. Having two variables with the same name is forbidden.

Added teardown to PetitCompilerTests to clean up a generated parser after tests.

Portability fix PPCAbstractCharacterNode>>body: use #storeString instead of #printString.

Fixed PPCGuard>>compileCharacter: Use #storeString instead of #printString - #storeString is defined as string whose evaluation would return the receiver (resp. object equal to reveiver).

Portability fix in PPCompiler>>cleanGeneratedMethods: Use more portable coding.

Portability - test if RPackageOrganizer is present... ...if not, do not register new package using it. RPackage is Pharo specific thing not present in other Smalltalks.

Override #new in classes that implement #initialize. Not all Smalltalks call #initialize automatically. Actually, mose of them does not.