[BUGFIX] Use raw flux field name where required and NULL must be avoided

This fixes an issue on 4.x branches when retrieving flexform variables; before this patch the internal getFieldName() was being used which would return NULL on 4.x branches, making getFlexFormValues() return too early.
Merge pull request #163 from NamelessCoder/rawfieldname

[BUGFIX] Use raw flux field name where required and NULL must be avoided
[TASK] Add a few core VH aliases to increase 4.5 compatibility
Merge pull request #164 from NamelessCoder/classaliashack

[TASK] Add a few core VH aliases to increase 4.5 compatibility