Misc fixes.
Implement PageUp/Down, Alt+Home/End and C-n/C-p

 - PageUp/Down move up or down to the first non-printed entry.
 - Alt+Home/End move to the start/end of the completion list.
 - C-n and C-p are aliases for Up/Down.
Implement style customization. Style are read from ~/.ocp-browser.

The syntax is the same as Xressources/utop :
```
Module.background: blue
```
Implement key bindings customization (in the same way than utop).
Enable all kinds by default for ocp-lambda. fix a bug with "-s k".