#187

Previously, if error occured during the creation of inner
type instance from iCalendar string, the error with the
name of the bogus property would be stored in the
appropriate component's errors attribute along with the error
string  but the property's value would be removed from the
parsed representation. This patch keeps the value even with its
parameters at that certain property, the value's type is changed
to vText.

Should allow implementation of
#158

Improves
#174

…ctionality change.