EnglishConstants constructor Null safety

1. text_analysis
2. constants
3. EnglishConstants
4. EnglishConstants constructor

EnglishConstants class

1. Constructors
2. EnglishConstants
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static methods
12. kLemmatizer
13. kStemmer
14. Constants
15. kAbbreviations
16. kSentenceDelimiter
17. kStopWords
18. reBracketsAndCarets
19. reLineEndingSelector
20. reNonWordChars
21. rePunctuationSelector
22. reSentenceEndingSelector
23. reWordChars
24. reWordEndsWithPeriod