DOC: fix typo in the body parser documentation for msg.sov

"positive" ... "null or positive". The second one is "null or negative".
BUG/MEDIUM: pattern: don't load more than once a pattern list.

A memory optimization can use the same pattern expression for many
equal pattern list (same parse method, index method and index_smp
method).

The pattern expression is returned by "pattern_new_expr", but this
function dont indicate if the returned pattern is already in use.

So, the caller function reload the list of patterns in addition with
the existing patterns. This behavior is not a problem with tree indexed
pattern, but it grows the lists indexed patterns.

This fix add a "reuse" flag in return of the function "pattern_new_expr".
If the flag is set, I suppose that the patterns are already loaded.

This fix must be backported into 1.5.
BUG/MINOR: peers: the buffer size is global.tune.bufsize, not trash.size

Currently this is harmless since trash.size is copied from
global.tune.bufsize, but this may soon change when buffers become
more dynamic.

At least for consistency it should be backported to 1.5.
BUG/MINOR: samples: fix unnecessary memcopy converting binary to string.
MINOR: sample: add a few basic internal fetches (nbproc, proc, stopping)

Sometimes, either for debugging or for logging we'd like to have a bit
of information about the running process. Here are 3 new fetches for this :

nbproc : integer
  Returns an integer value corresponding to the number of processes that were
  started (it equals the global "nbproc" setting). This is useful for logging
  and debugging purposes.

proc : integer
  Returns an integer value corresponding to the position of the process calling
  the function, between 1 and global.nbproc. This is useful for logging and
  debugging purposes.

stopping : boolean
  Returns TRUE if the process calling the function is currently stopping. This
  can be useful for logging, or for relaxing certain checks or helping close
  certain connections upon graceful shutdown.
MINOR: samples: adds the bytes converter.

bytes(<offset>[,<length>])
  Extracts a some bytes from an input binary sample. The result is a
  binary sample starting at an offset (in bytes) of the original sample
  and optionnaly truncated at the given length.
MINOR: samples: adds the field converter.

field(<index>,<delimiters>)
  Extracts the substring at the given index considering given delimiters from
  an input string. Indexes start at 1 and delimiters are a string formatted
  list of chars.