Merge branch 'ak/p4'

* ak/p4:
Utilise our new p4_read_pipe and p4_write_pipe wrappers
Add p4 read_pipe and write_pipe wrappers
Put in the two other configuration elements found in the source
Put some documentation in about the parameters that have been added
Move git-p4.syncFromOrigin into a configuration parameters section
Consistently use 'git-p4' for the configuration entries
If the user has configured various parameters, use them.
Switch to using 'p4_build_cmd'
If we are in verbose mode, output what we are about to run (or return)
Add a single command that will be used to construct the 'p4' command
Utilise the new 'p4_system' function.
Have a command that specifically invokes 'p4' (via system)
Utilise the new 'p4_read_pipe_lines' command
Create a specific version of the read_pipe_lines command for p4 invocations

Conflicts:
contrib/fast-import/git-p4

diff --cc contrib/fast-import/git-p4
index 3f2303dcf0267d17b66e37f0c06da60cef8fe70b,12fa9d3fd81ce83f53f36178bc3111edddfd2173..f9865b444fdf8b21211b04e9dba2999dd90cbc23
--- 1/contrib/fast-import/git-p4
--- 2/contrib/fast-import/git-p4
+++ b/contrib/fast-import/git-p4
@@@ -16,11 -16,41 +16,46 @@@ from sets import Set
  
  verbose = False
  
+ 
+ def p4_build_cmd(cmd):
+     """Build a suitable p4 command line.
+ 
+     This consolidates building and returning a p4 command line into one
+     location. It means that hooking into the environment, or other configuration
+     can be done more easily.
+     """
+     real_cmd = "%s " % "p4"
+ 
+     user = gitConfig("git-p4.user")
+     if len(user) > 0:
+         real_cmd += "-u %s " % user
+ 
+     password = gitConfig("git-p4.password")
+     if len(password) > 0:
+         real_cmd += "-P %s " % password
+ 
+     port = gitConfig("git-p4.port")
+     if len(port) > 0:
+         real_cmd += "-p %s " % port
+ 
+     host = gitConfig("git-p4.host")
+     if len(host) > 0:
+         real_cmd += "-h %s " % host
+ 
+     client = gitConfig("git-p4.client")
+     if len(client) > 0:
+         real_cmd += "-c %s " % client
+ 
+     real_cmd += "%s" % (cmd)
+     if verbose:
+         print real_cmd
+     return real_cmd
+ 
 +def chdir(dir):
 +    if os.name == 'nt':
 +        os.environ['PWD']=dir
 +    os.chdir(dir)
 +
  def die(msg):
      if verbose:
          raise Exception(msg)
@@@ -717,9 -764,9 +769,9 @@@ class P4Submit(Command)
          print "Perforce checkout for depot path %s located at %s" % (self.depotPath, self.clientPath)
          self.oldWorkingDirectory = os.getcwd()
  
 -        os.chdir(self.clientPath)
 +        chdir(self.clientPath)
          print "Syncronizing p4 checkout..."
-         system("p4 sync ...")
+         p4_system("sync ...")
  
          self.check()