Layout improvements

• #54 (closed) : Display Keynames instead of IDs (was: ID, NAME & co.)
• #73 (closed) : new panel to create keys from scratch
• #94 (closed) : change the way metadata are displayed
• #113 (closed) : distinguish between invalid keys and old version of valid keys
• #131 (closed) : Editable fields not copyable in read mode
• #155 (closed) : add search field in pk-list
• #156 (closed) : retrieve only valid keys from server in order to fill dropdown menus
• #157 (closed) : big dropdown content going out of screen
• #159 (closed) : add ancestor field

partially:

• #150 (closed) : reorganize top-level keys and add categories
• #159 (closed): update of the first row-view key is not properly handled