Much improved error messages for ca65. For most errors it will now say what

was expected and what was found instead. Also improved error recovery in a few
places.

test/asm/listing/130-errormsg.s

@@ -1,2 +1 @@
         lda     |
-

test/asm/listing/ref/120-errormsg.err2

@@ -0,0 +1 @@
+120-errormsg.s:1: Error: Expected 'end-of-line' but found '0'

test/asm/listing/ref/121-errormsg.err2

@@ -0,0 +1 @@
+121-errormsg.s:1: Error: Expected ':' after identifier to form a label but found 'end-of-line'

test/asm/listing/ref/122-errormsg.err2

@@ -0,0 +1 @@
+122-errormsg.s:1: Error: Expected a struct/union name but found 'X'

test/asm/listing/ref/123-errormsg.err2

@@ -0,0 +1 @@
+123-errormsg.s:1: Error: Expected 'end-of-line' but found 'foo'

test/asm/listing/ref/124-errormsg.err2

@@ -0,0 +1 @@
+124-errormsg.s:1: Error: Expected 'Y' but found 'A'

test/asm/listing/ref/125-errormsg.err2

@@ -0,0 +1,2 @@
+125-errormsg.s:1: Error: Expected 'X' or 'S' but found 'A'
+125-errormsg.s:1: Error: Illegal addressing mode

test/asm/listing/ref/126-errormsg.err2

@@ -0,0 +1 @@
+126-errormsg.s:2: Error: Expected a storage allocator after the field name but found 'end-of-line'

test/asm/listing/ref/127-errormsg.err2

@@ -0,0 +1 @@
+127-errormsg.s:1: Error: Expected a mnemonic but found '127'

test/asm/listing/ref/128-errormsg.err2

@@ -0,0 +1 @@
+128-errormsg.s:1: Error: Expected ',' but found 'end-of-line'

test/asm/listing/ref/129-errormsg.err2

@@ -0,0 +1 @@
+129-errormsg.s:1: Error: Expected ',' but found 'end-of-line'

test/asm/listing/ref/130-errormsg.err2

@@ -0,0 +1,2 @@
+130-errormsg.s:1: Error: Expected an expression but found '|'
+130-errormsg.s:1: Error: Expected an expression but found 'end-of-line'

test/asm/listing/ref/131-errormsg.err2

@@ -0,0 +1 @@
+131-errormsg.s:1: Error: Expected 'end-of-line' but found '1'