Extend generaloption

More generaloption features:
* add / add_first action
* strlistpath / strtuplepath type
* configfiles initenv
We should still care, until EasyBuild v2.0 is out...

```
jenkins@jenkins1:~$ /var/lib/jenkins/.local/bin/python2.4
Python 2.4.6 (#2, Nov 16 2013, 14:19:58) 
[GCC 4.7.2] on linux3
Type "help", "copyright", "credits" or "license" for more information.
>>> d={}
>>> d.foo
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
AttributeError: 'dict' object has no attribute 'foo'
>>> try:
...  d.foo
... except AttributeError, err:
...  msg = str(err)
... 
>>> msg
"'dict' object has no attribute 'foo'"
```