Added nsExec.dll and readme file

git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@928 212acab6-be3b-0410-9dea-997c60f758d6

Contrib/nsExec/nsExec.txt

@@ -0,0 +1,27 @@
+nsExec
+------
+nsExec will execute command-line based programs and capture the output
+without opening a dos box.
+
+Usage
+-----
+nsExec::Exec path [/TIMEOUT=x]
+
+-or-
+
+nsExec::ExecToLog path [/TIMEOUT=x]
+
+Both functions are the same except ExecToLog will print the output
+to the logwindow.
+
+The timeout value is optional and is used to set the time in 
+milliseconds for the dll to wait for the process to return
+before it quits.
+
+Return Value
+------------
+If nsExec is unable to execute the process, it will return "error"
+on the top of the stack, else it returns "success".
+
+
+Copyright (c) 2002 Robert Rainwater