Galaga: small fix and some notes. [Couriersud]

- leave some more information about the equivalent galois LFSR like
  taps and seed values.
- All members are now initialized by constructor.

src/mame/includes/galaga.h

@@ -34,6 +34,10 @@ public:
 		, m_palette(*this, "palette")
 		, m_leds(*this, "led%u", 0U)
 		, m_starfield(*this, "starfield")
+		, m_galaga_gfxbank(0)
+		, m_main_irq_mask(0)
+		, m_sub_irq_mask(0)
+		, m_sub2_nmi_mask(0)
 	{ }
 
 	DECLARE_READ8_MEMBER(bosco_dsw_r);

src/mame/video/starfield_05xx.cpp

@@ -288,6 +288,16 @@
            the Fibonacci form, which is why the latter is used in this 
            implementation.
 
+           The LFSR used by Wolfgang and Jindřich had taps at 15, 12, 10 and 5.
+           With the same seed values, the following holds true:
+
+           Decode_W(lfsr[t-4]) = Decode_J(lfsr[t])
+
+           The two decoding algorithm (Wolfgang, Jindřich) thus delivered the
+           same results but with a 4 clock difference.
+
+           Jindřich: Seed Value 0x70cc
+           Wolfgang: Seed Value 0xe7bf
           ---------------------------------------------------------------------------