Release NanoBoyAdvance 1.8.1

A cycle-accurate Nintendo Game Boy Advance emulator.

Please backup your save files before updating to be safe.
Changelog

UI: implement an option to pause the emulator when the window is inactive
UI: improve lack of response to input changes in the sprite viewer when the emulator is paused
UI: replace QOpenGLWidget with QWidget (thanks @GranMinigun)
UI: fix solar sensor level menu that has been broken in 1.8.0 (fixes #370)
GPIO: fix broken deserialization of port directions
APU: MP2K HLE: handle corrupted wave info addresses (fixes #362)
APU: PSG L/R volume must be remapped from 0-7 to 1-8
GameDB: Japanese Boktai releases have a solar sensor (thanks @raphaelr)
Redirect stdout on Windows (thanks @GranMinigun)