- flexran_agent_ue_config_reply() and flexran_agent_ue_state_change() send
  slice_id

Incoming slice configuration changes are buffered in an intermediate structure.
The MAC scheduler periodically polls the agent about changes. If there has been
a slice configuration change, apply it.

adds support for:
* create/remove slices
* change UE-slice association
* read/write slice parameters
* find slice index via ID

slice_counter had a wrong condition, not scheduling in DLSCH if the number of
slices is greater than one

- introduce structure in RC for slicing conf (UL/DL)
- move global variables regarding slice configuration into RC
- change ue_slice_membership(): consider UL/DL
- remove the unnecessary header files
- set default parameters: one slice

Use common log mechanism in layer 3, mapping specific macros to common ones and extending common log utilities to support specific layer3 requirements

LOG_F replaced by LOG_DUMPMSG. Add a generic function to dump a buffer or message. Go on with LOG_M implementation improvement. Remove redundant options to enable/disable logs.