fix: make GridActivity singleton as it feels more natural to have only one instance of the app.
fix: make GridActivity singleton as it feels more natural to have only one instance of the app.

hujiaweibujidao/textfairy,renard314/textfairy,renard314/textfairy,sachinxagrawal/testocr,dankito/TextFairyPlugin,renard314/textfairy,hujiaweibujidao/textfairy,sachinxagrawal/testocr,renard314/textfairy,sachinxagrawal/testocr,dankito/TextFairyPlugin,sachinxagrawal/testocr,renard314/textfairy,dankito/TextFairyPlugin,hujiaweibujidao/textfairy,dankito/TextFairyPlugin,sachinxagrawal/testocr,dankito/TextFairyPlugin,renard314/textfairy,renard314/textfairy,renard314/textfairy,hujiaweibujidao/textfairy,hujiaweibujidao/textfairy