refactor: export semester and year generator from period file and fix a test in local datetime

Author: FMorschel

lib/period.dart

@@ -18,8 +18,6 @@ library period;
 
 import 'src/enums/enums.dart' show PeriodGenerator;
 import 'src/period_generators/period_generators.dart';
-import 'src/period_generators/semester_generator.dart';
-import 'src/period_generators/year_generator.dart';
 import 'src/periods/periods.dart';
 
 export 'src/enums/enums.dart' show Month, PeriodGenerator, Week, Weekday;

lib/src/enums/period_generator.dart

@@ -1,6 +1,4 @@
 import '../period_generators/period_generators.dart';
-import '../period_generators/semester_generator.dart';
-import '../period_generators/year_generator.dart';
 import '../periods/periods.dart';
 
 /// An enumeration of the different period generators implemented in this

test/period_generators/fortnight_generator_test.dart

@@ -1,8 +1,6 @@
 // ignore_for_file: prefer_const_constructors
 
 import 'package:due_date/period.dart';
-import 'package:due_date/src/period_generators/semester_generator.dart';
-import 'package:due_date/src/period_generators/year_generator.dart';
 import 'package:test/test.dart';
 import 'package:time/time.dart';
 

test/period_generators/hour_generator_test.dart

@@ -1,8 +1,6 @@
 // ignore_for_file: prefer_const_constructors
 
 import 'package:due_date/period.dart';
-import 'package:due_date/src/period_generators/semester_generator.dart';
-import 'package:due_date/src/period_generators/year_generator.dart';
 import 'package:test/test.dart';
 
 void main() {

test/period_generators/minute_generator_test.dart

@@ -1,8 +1,6 @@
 // ignore_for_file: prefer_const_constructors
 
 import 'package:due_date/period.dart';
-import 'package:due_date/src/period_generators/semester_generator.dart';
-import 'package:due_date/src/period_generators/year_generator.dart';
 import 'package:test/test.dart';
 
 void main() {

test/period_generators/month_generator_test.dart

@@ -1,8 +1,6 @@
 // ignore_for_file: prefer_const_constructors
 
 import 'package:due_date/period.dart';
-import 'package:due_date/src/period_generators/semester_generator.dart';
-import 'package:due_date/src/period_generators/year_generator.dart';
 import 'package:test/test.dart';
 import 'package:time/time.dart';
 

test/period_generators/second_generator_test.dart

@@ -1,8 +1,6 @@
 // ignore_for_file: prefer_const_constructors
 
 import 'package:due_date/period.dart';
-import 'package:due_date/src/period_generators/semester_generator.dart';
-import 'package:due_date/src/period_generators/year_generator.dart';
 import 'package:test/test.dart';
 
 void main() {

test/period_generators/semester_generator_test.dart

@@ -1,7 +1,6 @@
 // ignore_for_file: prefer_const_constructors
 
 import 'package:due_date/period.dart';
-import 'package:due_date/src/period_generators/semester_generator.dart';
 import 'package:test/test.dart';
 import 'package:time/time.dart';
 

test/period_generators/week_generator_test.dart

@@ -1,8 +1,6 @@
 // ignore_for_file: prefer_const_constructors
 
 import 'package:due_date/period.dart';
-import 'package:due_date/src/period_generators/semester_generator.dart';
-import 'package:due_date/src/period_generators/year_generator.dart';
 import 'package:test/test.dart';
 import 'package:time/time.dart';
 

test/period_generators/year_generator_test.dart

@@ -1,7 +1,6 @@
 // ignore_for_file: prefer_const_constructors
 
 import 'package:due_date/period.dart';
-import 'package:due_date/src/period_generators/year_generator.dart';
 import 'package:test/test.dart';
 import 'package:time/time.dart';