Add some missing preprocessing #import directives

Fixes most GCC warnings of form:
	warning: @interface of class ‘MyClass’ not found

SoObjects/Appointments/SOGoAppointmentFolder.m

@@ -30,6 +30,7 @@
 
 #import <NGObjWeb/NSException+HTTP.h>
 #import <NGObjWeb/SoObject+SoDAV.h>
+#import <NGObjWeb/WOApplication.h>
 #import <NGObjWeb/WOContext+SoObjects.h>
 #import <NGObjWeb/WOMessage.h>
 #import <NGObjWeb/WORequest.h>

SoObjects/Mailer/SOGoMailAccounts.m

@@ -25,6 +25,7 @@
 
 #import <NGObjWeb/NSException+HTTP.h>
 #import <NGObjWeb/WOContext+SoObjects.h>
+#import <NGObjWeb/WORequest.h>
 #import <NGExtensions/NSNull+misc.h>
 #import <NGExtensions/NSObject+Logs.h>
 #import <DOM/DOMElement.h>

UI/Contacts/UIxContactFolderActions.m

@@ -35,6 +35,7 @@
 #import <NGExtensions/NSString+misc.h>
 #import <NGExtensions/NSNull+misc.h>
 #import <NGExtensions/NGBase64Coding.h>
+#import <NGHttp/NGHttpRequest.h>
 #import <NGMime/NGMimeMultipartBody.h>
 
 #import <Contacts/SOGoContactObject.h>

UI/MailPartViewers/UIxMailPartICalActions.m

@@ -19,6 +19,7 @@
  */
 
 #import <Foundation/NSCalendarDate.h>
+#import <Foundation/NSDictionary.h>
 #import <Foundation/NSEnumerator.h>
 #import <Foundation/NSValue.h>
 

UI/MainUI/SOGoMicrosoftActiveSyncActions.m

@@ -26,6 +26,7 @@
 #import <SOGo/SOGoFolder.h>
 
 #import <NGObjWeb/NSException+HTTP.h>
+#import <NGObjWeb/WOContext.h>
 #import <NGObjWeb/WODirectAction.h>
 #import <NGObjWeb/WORequest.h>
 #import <NGObjWeb/WOResponse.h>

UI/Scheduler/UIxAppointmentActions.m

@@ -24,6 +24,7 @@
 #import <Foundation/NSDictionary.h>
 #import <Foundation/NSString.h>
 #import <Foundation/NSArray.h>
+#import <Foundation/NSValue.h>
 
 #import <NGExtensions/NSObject+Values.h>