fix CGUIDialogPeripheralSettings
fix multiple setting dependencies on the same setting
remember setting level
don't allow empty strings for integer/number settings
always reset invalid setting controls when switching to another control
CSetting: add CheckValidity()
WIP: guilib: add invalid input state to CGUIButtonControl

This adds HasInvalidInput(), SetInvalidInput(), GUI_MSG_INPUT_VALID and
GUI_MSG_INPUT_INVALID to CGUIButtonControl et. al. Furthermore the following
tags have been added for skins: <textureinvalid>, <alttextureinvalid> and
<invalidcolor>.
[confluence] add <textureinvalid> in SettingsCategory.xml
CGUIWindowSettingsCategory: check and update setting control validity after every action
settings.xml: add <minimum> and <maximum> for ports
fix confluence
fix invalid value with delayed settings
move logic to handle network-based services from CApplication to CNetworkServices
settings: execute OnSettingChanging() if OnSettingChanging() failed to give callback handlers a chance to revert any changes made
CSettings: fix OnSettingChanging() during Load()
fix networkservices
move setting changed logic to callbacks
CGUIWindowSettingsCategory: don't reset delayed setting on GUI_MSG_WINDOW_RESIZE
CGUIWindowSettingsCategory: fix setting control not being updated if changing a setting fails
fix settings.xml