In the configuration file, to enable measurements, add:

    enable_measurement_reports = "yes";

Note that if x2 is enabled then the option 'enable_measurement_reports'
is not taken into account and the measurements are enabled.

This commit introduces X2AP timers (t_reloc_prep, tx2_reloc_overall).
You need to set the values in the configuration file.

X2AP can be enabled or disabled in the configuration file too (disabled
by default).

Some deadcode was removed.

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>