Merge branch 'next'

* next: (21 commits)
  chore, also let localSymbol default to ccy for cash `contracts'
  minor, when creating cash positions as contract
  minor, fall back to primary exchange if exchange slot in contract isn't set in tws_cont_nick()
  chore, kick RMETA case altogether
  minor, support tws attributes in qmeta
  minor, actually send position reports on the wire
  minor, import strops.h (for fixc serialisation)
  minor, connect to beef channels in pf-tws
  minor, bring back pf-tws (as known from unsermarkt)
  minor, provide tws_sub_ac() and tws_rem_ac() in tws core
  minor, provide pfa.[ch] in analogy to quo.[ch]
  fix, PEBKAC, include string.h in sdef-fixml.cpp as needed for memcpy()
  chore, actually include sdef.h in sdef-seria.h as we use tws_const_sdef_t objects in our signature
  chore, provide conditional SDEF_WRONLY to emit only serialising code (no deser goodness)
  chore, split sdef-private.h into deser guts and put serialiser goodness into sdef-seria.h
  chore, daemonise early
  minor, adapt pf-tws to recent refactorings, tws-sock and tws-uri
  chore, adapt quo-tws to tws-sock refactoring
  minor, refactor make_{dccp,tcp}() and tws_sock() into tws-sock.[ch]
  chore, adapt quo-tws to using tws-uri.[ch]
  ...