fix: Quote CL cmd in iCmd5250 for shell escaping

iCmd5250 is just a fancy wrapper around iSh, using the PASE system
command. It did not do any shell escaping/quoting, so it basically only
allowed calling CL commands without parameters or with only positional
parameters because the parentheses would cause the shell to gack.

eg.
iCmd5250('wrkactjob', 'WRKACTJOB SBS(QBATCH)')

basically became

iSh('wrkactjob', '/QOpenSys/usr/bin/system WRKACTJOB SBS(QBATCH)')

When executed, an error would be given from the shell:

sh: syntax error at line 1 : `(' unexpected

The proper fix is to quote the string, but that can be tricky to get
right. Luckily, Python has shlex.quote to do the hard work for us.
https://docs.python.org/3/library/shlex.html#shlex.quote

Fixes #49

Author: kadler

src/itoolkit/itoolkit.py

@@ -113,6 +113,7 @@ class iXml(iBase):          IBM i XMLSERVICE raw xml input
 import re
 import time
 
+from shlex import quote
 
 class iBase(object): # noqa N801
     """
@@ -329,7 +330,7 @@ class iCmd5250(iSh): # noqa N801
     """
 
     def __init__(self, ikey, icmd, iopt={}):
-        cmd = "/QOpenSys/usr/bin/system " + icmd
+        cmd = "/QOpenSys/usr/bin/system " + quote(icmd)
         super(iCmd5250, self).__init__(ikey, cmd, iopt)