Allow $...$ and $x$ latex fragment types at beginning of line

* lisp/org.el (org-latex-regexps): Allow matching latex fragments of
  type "$" and "$1" at beginning of line.

lisp/org.el

@@ -16483,8 +16483,8 @@ The images can be removed again with \\[org-ctrl-c-ctrl-c]."
   '(("begin" "^[ \t]*\\(\\\\begin{\\([a-zA-Z0-9\\*]+\\)[^\000]+?\\\\end{\\2}\\)" 1 t)
     ;; ("$" "\\([ 	(]\\|^\\)\\(\\(\\([$]\\)\\([^ 	\r\n,.$].*?\\(\n.*?\\)\\{0,5\\}[^ 	\r\n,.$]\\)\\4\\)\\)\\([ 	.,?;:'\")]\\|$\\)" 2 nil)
     ;; \000 in the following regex is needed for org-inside-LaTeX-fragment-p
-    ("$1" "\\([^$]\\)\\(\\$[^ 	\r\n,;.$]\\$\\)\\([- 	.,?;:'\")\000]\\|$\\)" 2 nil)
-    ("$" "\\([^$]\\)\\(\\(\\$\\([^ 	\r\n,;.$][^$\n\r]*?\\(\n[^$\n\r]*?\\)\\{0,2\\}[^ 	\r\n,.$]\\)\\$\\)\\)\\([- 	.,?;:'\")\000]\\|$\\)" 2 nil)
+    ("$1" "\\([^$]\\|^\\)\\(\\$[^ 	\r\n,;.$]\\$\\)\\([- 	.,?;:'\")\000]\\|$\\)" 2 nil)
+    ("$" "\\([^$]\\|^\\)\\(\\(\\$\\([^ 	\r\n,;.$][^$\n\r]*?\\(\n[^$\n\r]*?\\)\\{0,2\\}[^ 	\r\n,.$]\\)\\$\\)\\)\\([- 	.,?;:'\")\000]\\|$\\)" 2 nil)
     ("\\(" "\\\\([^\000]*?\\\\)" 0 nil)
     ("\\[" "\\\\\\[[^\000]*?\\\\\\]" 0 nil)
     ("$$" "\\$\\$[^\000]*?\\$\\$" 0 nil))