Avoid special characters as draw arguments

Always use DecodeUrlOptionValue method when processing URL arguments
or URL string. Internally method provides escape symbols for quotes and backslash.
If expecting numeric value - remove all symbols
keeping alphanumeric, '.', '+', '-' and ':'

It allows to deserialize post data as ROOT object when processing exe.json request.
While this can leads to arbitrary code loading and injection, disable this feature by default.
Can be enabled back with:
 ```
serv->SetAllowPostObject(kTRUE);
```

While here arbitrary string injected into ProcessLine,
ensure that only numeric argument is not quoted.
All other arguments kinds will be quoted and prevent execution of potentially dangerous code

Verify execution of several supported requests
which can be handled by http server. Testing:
   - root.json
   - root.xml
   - file.root
   - exe.json
   - exe.json with POST data
   - item.json
   - cmd.json
   - multi.json

Also verify basic functionality of
TRootSniffer::DecodeUrlOptionValue method