Moving global settings for crengine to ./data/cr3.ini

1. On making "dummy" document, crengine will try to read & apply settings from ./data/cr3.ini. If it founds nothing, it will create this file with default values.
2. Function to save global defaults for crengine - saveDefaults. One may call this function either i) on the user's manual request or ii) everytime just before crengine closes document (so crengine will remember last configuration)