patch 8.2.0156: various typos in source files and tests

Problem:    Various typos in source files and tests.
Solution:   Fix the typos. (Emir Sari, closes #5532)
diff --git a/src/libvterm/t/41screen_unicode.test b/src/libvterm/t/41screen_unicode.test
index 79dcb68..6f5602d 100644
--- a/src/libvterm/t/41screen_unicode.test
+++ b/src/libvterm/t/41screen_unicode.test
@@ -40,7 +40,7 @@
 PUSH  "\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81\xCC\x81"
   ?screen_cell 0,0 = {0x65,0x301,0x301,0x301,0x301,0x301} width=1 attrs={} fg=rgb(240,240,240) bg=rgb(0,0,0)
 
-!Outputing CJK doublewidth in 80th column should wraparound to next line and not crash"
+!Outputting CJK doublewidth in 80th column should wraparound to next line and not crash"
 RESET
 PUSH "\e[80G\xEF\xBC\x90"
   ?screen_cell 0,79 = {} width=1 attrs={} fg=rgb(240,240,240) bg=rgb(0,0,0)