[modules] start pimping dependencies

Start working on #940

This replaces
```xml
<depend require="foo|bar" conflict="baz"/>
```
with
```xml
<depends>foo,bar</depends>
<conflicts>baz</conflicts>
```

and now allows to specify OR dependencies with | (pipe) similaro to Debian depends:
```xml
<depends>foo,bar,this|that</depends>
```
which would depend on: foo AND bar AND (this OR that)
Presumably you mean <depends> here.