Export multiple MQ4 codes at once + MagicNumber handling

1. we'll modify databank buttons a bit. We'll remove Export menu and all the items in Export will be moved to Save button. Save will become combo button, and its first item will be "Save to .sq4"

2. we'll add possibility for mass-saving files to MQL - see screenshot from SQ3 how I mean it

3. Mass file save dialog will be modified a little, see screenshot

3. New Mass Source code save dialog will look like in the screenshot - there will be a special feature to modify Magic Number variable(s) for every saved strategy, so that no strategy shares the same Magic Number. It will be done by simple text search and replacement in the generated source file, before it is saved to disc.
Keep in mind that strategy could have multiple Magic Number variables, for example MagicNumberLong, MagicNumberShort. Each number should be incremented by one.
You should search for "int MagicNumber*" in the generated source file.