CCRouter and CCUrl fixes, CCArr documentation and minor cleanup

### CCRouter ###
- Using `#` as regex delimiters
 - `#` is one of the only character not used in server side urls
 - until now you used `~` which broke urls like http://example.com/~username
- in `_init()` I defined some escapes which will be applied before the default [num|any|*]-filter
 - I hope I have all important ones
 - `[` or `]` aren't needed because they could break the other filters and are blocked by apache (someone should check nginx - I think they could be possible by the RFCs)

### CCUrl ###
- Scenario: http://example.com/?test[a][b]=z&test[a][c]=z
- in `CCUrl::to()` the `$params` would contain: ```
"test" => array(
  "a" => array(
    "b" => "z",
    "c" => "z"
  )
)```
- I fear many other methods and classes must be updated for such parameter...

### CCArr ###
#### is_multi ####
- Wont work on ```
array( array() )```
- Typo in function name

#### is_collection ####
- Only checks first value
- Same description as `is_multi`?

#### Suggestion ####
- to remove or rename `is_collection` or `is_multi`
- implement function in which **one** element must be an array
- implement function in which **all** elements must be an array
- Short discussion? :wink: