patch 8.2.0795: libvterm code lags behind the upstream version

Problem:    Libvterm code lags behind the upstream version.
Solution:   Include revisions 748 - 754.
diff --git a/src/libvterm/t/60screen_ascii.test b/src/libvterm/t/60screen_ascii.test
index c2f48fa..e679b98 100644
--- a/src/libvterm/t/60screen_ascii.test
+++ b/src/libvterm/t/60screen_ascii.test
@@ -1,12 +1,12 @@
 INIT
-WANTSCREEN c
+WANTSCREEN ac
 
 !Get
 RESET
 PUSH "ABC"
   movecursor 0,3
-  ?screen_chars 0,0,1,3 = 0x41,0x42,0x43
-  ?screen_chars 0,0,1,80 = 0x41,0x42,0x43
+  ?screen_chars 0,0,1,3 = "ABC"
+  ?screen_chars 0,0,1,80 = "ABC"
   ?screen_text 0,0,1,3 = 0x41,0x42,0x43
   ?screen_text 0,0,1,80 = 0x41,0x42,0x43
   ?screen_cell 0,0 = {0x41} width=1 attrs={} fg=rgb(240,240,240) bg=rgb(0,0,0)
@@ -18,11 +18,11 @@
   ?screen_eol 0,3 = 1
 PUSH "\e[H"
   movecursor 0,0
-  ?screen_chars 0,0,1,80 = 0x41,0x42,0x43
+  ?screen_chars 0,0,1,80 = "ABC"
   ?screen_text 0,0,1,80 = 0x41,0x42,0x43
 PUSH "E"
   movecursor 0,1
-  ?screen_chars 0,0,1,80 = 0x45,0x42,0x43
+  ?screen_chars 0,0,1,80 = "EBC"
   ?screen_text 0,0,1,80 = 0x45,0x42,0x43
 
 WANTSCREEN -c
@@ -37,33 +37,33 @@
 RESET
 PUSH "ABC\e[H\e[@"
 PUSH "1"
-  ?screen_chars 0,0,1,80 = 0x31,0x41,0x42,0x43
+  ?screen_chars 0,0,1,80 = "1ABC"
 
 RESET
 PUSH "ABC\e[H\e[P"
-  ?screen_chars 0,0,1,1 = 0x42
-  ?screen_chars 0,1,1,2 = 0x43
-  ?screen_chars 0,0,1,80 = 0x42,0x43
+  ?screen_chars 0,0,1,1 = "B"
+  ?screen_chars 0,1,1,2 = "C"
+  ?screen_chars 0,0,1,80 = "BC"
 
 !Space padding
 RESET
 PUSH "Hello\e[CWorld"
-  ?screen_chars 0,0,1,80 = 0x48,0x65,0x6c,0x6c,0x6f,0x20,0x57,0x6f,0x72,0x6c,0x64
+  ?screen_chars 0,0,1,80 = "Hello World"
   ?screen_text 0,0,1,80 = 0x48,0x65,0x6c,0x6c,0x6f,0x20,0x57,0x6f,0x72,0x6c,0x64
 
 !Linefeed padding
 RESET
 PUSH "Hello\r\nWorld"
-  ?screen_chars 0,0,2,80 = 0x48,0x65,0x6c,0x6c,0x6f,0x0a,0x57,0x6f,0x72,0x6c,0x64
+  ?screen_chars 0,0,2,80 = "Hello\nWorld"
   ?screen_text 0,0,2,80 = 0x48,0x65,0x6c,0x6c,0x6f,0x0a,0x57,0x6f,0x72,0x6c,0x64
 
 !Altscreen
 RESET
 PUSH "P"
-  ?screen_chars 0,0,1,80 = 0x50
+  ?screen_chars 0,0,1,80 = "P"
 PUSH "\e[?1049h"
   ?screen_chars 0,0,1,80 = 
 PUSH "\e[2K\e[HA"
-  ?screen_chars 0,0,1,80 = 0x41
+  ?screen_chars 0,0,1,80 = "A"
 PUSH "\e[?1049l"
-  ?screen_chars 0,0,1,80 = 0x50
+  ?screen_chars 0,0,1,80 = "P"