patch 8.0.0902: cannot specify directory or environment for a job

Problem:    Cannot specify directory or environment for a job.
Solution:   Add the "cwd" and "env" arguments to job options. (Yasuhiro
            Matsumoto, closes #1160)

runtime/doc/channel.txt

@@ -427,8 +427,8 @@ When no message was available then the result is v:none for a JSON or JS mode
 channels, an empty string for a RAW or NL channel.  You can use |ch_canread()|
 to check if there is something to read.
 
-Note that when there is no callback message are dropped.  To avoid that add a
-close callback to the channel.
+Note that when there is no callback, messages are dropped.  To avoid that add
+a close callback to the channel.
 
 To read all output from a RAW channel that is available: >
 	let output = ch_readraw(channel)
@@ -475,11 +475,6 @@ it like this: >
 Without the handler you need to read the output with |ch_read()| or
 |ch_readraw()|. You can do this in the close callback, see |read-in-close-cb|.
 
-Note that if the job exits before you read the output, the output may be lost.
-This depends on the system (on Unix this happens because closing the write end
-of a pipe causes the read end to get EOF).  To avoid this make the job sleep
-for a short while before it exits.
-
 The handler defined for "out_cb" will not receive stderr.  If you want to
 handle that separately, add an "err_cb" handler: >
     let job = job_start(command, {"out_cb": "MyHandler",
@@ -494,6 +489,11 @@ started job gets the focus.  To avoid that, use the `foreground()` function.
 This might not always work when called early, put in the callback handler or
 use a timer to call it after the job has started.
 
+Depending on the system, starting a job can put Vim in the background, the
+started job gets the focus.  To avoid that, use the `foreground()` function.
+This might not always work when called early, put in the callback handler or
+use a timer to call it after the job has started.
+
 You can send a message to the command with ch_evalraw().  If the channel is in
 JSON or JS mode you can use ch_evalexpr().
 
@@ -696,6 +696,10 @@ See |job_setoptions()| and |ch_setoptions()|.
 "block_write": number	only for testing: pretend every other write to stdin
 			will block
 
+"env": dict		environment variables for the new process
+"cwd": "/path/to/dir"	current working directory for the new process;
+			if the directory does not exist an error is given
+
 
 Writing to a buffer ~
 							*out_io-buffer*
@@ -731,10 +735,6 @@ The "out_msg" option can be used to specify whether a new buffer will have the
 first line set to "Reading from channel output...".  The default is to add the
 message.  "err_msg" does the same for channel error.
 
-'modifiable' option off, or write to a buffer that has 'modifiable' off.  That
-means that lines will be appended to the buffer, but the user can't easily
-change the buffer.
-
 When an existing buffer is to be written where 'modifiable' is off and the
 "out_modifiable" or "err_modifiable" options is not zero, an error is given
 and the buffer will not be written to.