#1244 Use [].copy and path.exists instead of more cumbersome solutions

#1244 Slightly optimized create_highlighted_versions.py so that it won't walk the source path when it should be skipping the file

#1244 Updated README.md in plaintext source folder

#1244 Added extra option loading from `bat_options` file in directory and significantly reduced size of plaintext source

#1244 Updated create_highlighted_versions.py to ignore README.md files and use the --show-all option for manually-defined binary files

#1244 Updated plaintext file with command

bat -A --no-config --style=plain --color=always --theme='1337' --italic-text=always src/Plaintext/plaintext.txt > highlighted/Plaintext/plaintext.txt

#1244 Added example plaintext file

tests/syntax-tests/highlighted/Plaintext/plaintext.txt

@@ -0,0 +1,178 @@
+␀␊
+\u{1}␊
+\u{2}␊
+\u{3}␊
+\u{4}␊
+\u{5}␊
+\u{6}␊
+␇␊
+␈␊
+├──┤␊
+␊
+␊
+\u{b}␊
+\u{c}␊
+␊
+\u{e}␊
+\u{f}␊
+\u{10}␊
+\u{11}␊
+\u{12}␊
+\u{13}␊
+\u{14}␊
+\u{15}␊
+\u{16}␊
+\u{17}␊
+\u{18}␊
+\u{19}␊
+\u{1a}␊
+␛␊
+\u{1c}␊
+\u{1d}␊
+\u{1e}␊
+\u{1f}␊
+·␊
+!␊
+"␊
+#␊
+$␊
+%␊
+&␊
+'␊
+(␊
+)␊
+*␊
++␊
+,␊
+-␊
+.␊
+/␊
+0␊
+1␊
+2␊
+3␊
+4␊
+5␊
+6␊
+7␊
+8␊
+9␊
+:␊
+;␊
+<␊
+=␊
+>␊
+?␊
+@␊
+A␊
+B␊
+C␊
+D␊
+E␊
+F␊
+G␊
+H␊
+I␊
+J␊
+K␊
+L␊
+M␊
+N␊
+O␊
+P␊
+Q␊
+R␊
+S␊
+T␊
+U␊
+V␊
+W␊
+X␊
+Y␊
+Z␊
+[␊
+\␊
+]␊
+^␊
+_␊
+`␊
+a␊
+b␊
+c␊
+d␊
+e␊
+f␊
+g␊
+h␊
+i␊
+j␊
+k␊
+l␊
+m␊
+n␊
+o␊
+p␊
+q␊
+r␊
+s␊
+t␊
+u␊
+v␊
+w␊
+x␊
+y␊
+z␊
+{␊
+|␊
+}␊
+~␊
+\u{7f}␊
+\u{80}␊
+\u{81}␊
+\u{82}␊
+\u{83}␊
+\u{84}␊
+\u{85}␊
+\u{86}␊
+\u{87}␊
+\u{88}␊
+\u{89}␊
+\u{8a}␊
+\u{8b}␊
+\u{8c}␊
+\u{8d}␊
+\u{8e}␊
+\u{8f}␊
+\u{90}␊
+\u{91}␊
+\u{92}␊
+\u{93}␊
+\u{94}␊
+\u{95}␊
+\u{96}␊
+\u{97}␊
+\u{98}␊
+\u{99}␊
+\u{9a}␊
+\u{9b}␊
+\u{9c}␊
+\u{9d}␊
+\u{9e}␊
+\u{9f}␊
+\u{a0}␊
+\u{a1}␊
+\u{a2}␊
+\u{a3}␊
+\u{a4}␊
+\u{a5}␊
+\u{a6}␊
+\u{a7}␊
+\u{a8}␊
+\u{a9}␊
+\u{aa}␊
+\u{ab}␊
+\u{ac}␊
+\u{ad}␊
+\u{ae}␊
+␊
+Here's·a·line·with·multiple·characters.