New interface: collect git status as enum

[wyrnat]

[what]
create a method which returns the filestatus of the git repository. Same as collect_status but instead of status information as string, enums are used

[why]
status() function was before only used as debug or test function. Therefore a string was fine. Now, the library taskolib needs to use this function for decision making. Therefore a string is overkill and an enum does the job.

[how]

• create a struct which consists of following elements
  • optional string as old path
  • optional string as new path
  • handlung status as an enum
  • change status as an enum

Old path is important for renamed or deleted files, new path for everything else.

[Finii]

Now, the library taskolib needs to use this function for decision making.

This is not the case anymore with my recent additions, so there is not really a strong need for the enums anymore.