various scripts - reverted the calls to io_popen and os_execute back

to the respective lua calls.

tools/executable_manager.lua

@@ -76,7 +76,7 @@ local function grep(file, pattern)
   if dt.configuration.running_os == "windows" then
     -- use find to get the matches
     local command = "\\windows\\system32\\find.exe " .. "\"" .. pattern .. "\"" .. " " .. file
-    local f = dtsys.io_popen(command)
+    local f = io.popen(command)
     local output = f:read("all")
     f:close()
     -- strip out the first line
@@ -85,7 +85,7 @@ local function grep(file, pattern)
   else
     -- use grep and just return the answers
     local command = "grep " .. pattern .. " " .. file
-    local f = dtsys.io_popen(command)
+    local f = io.popen(command)
     local output = f:read("all")
     f:close()
     result = du.split(output, "\n")