Remove dead code from features.c; refactor pickup code into pickup.c

This patch does the following:
 * It moves the pickup code out of features.c and into pickup.c
 * It removes the vast majority of dead code out of features.c. In particular,
   this includes the parking code.

(issue ASTERISK-22134)



git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@396060 f38db490-d61c-443f-a65b-d21fe96a405b
Add pickup.h include lines for chan_dahdi and chan_mgcp


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@396061 f38db490-d61c-443f-a65b-d21fe96a405b