Use script local variable instead of buffer local

autoload/vimwiki/html.vim

@@ -768,9 +768,10 @@ function! s:process_tag_math(line, math) "{{{
     let class = matchstr(a:line, '{{$\zs.*$')
     "FIXME class cannot be any string!
     let class = substitute(class, '\s\+$', '', 'g')
-    " Check the math placeholder (default: displaymath)
-    let b:vimwiki_mathEnv = matchstr(class, '^%\zs\S\+\ze%')
-    if b:vimwiki_mathEnv != ""
+    " store the environment name in a global variable in order to close the
+    " environment properly
+    let s:current_math_env = matchstr(class, '^%\zs\S\+\ze%')
+    if s:current_math_env != ""
       call add(lines, substitute(class, '^%\(\S\+\)%','\\begin{\1}', ''))
     elseif class != ""
       call add(lines, "\\\[".class)
@@ -781,8 +782,8 @@ function! s:process_tag_math(line, math) "{{{
     let processed = 1
   elseif math[0] && a:line =~ '^\s*}}\$\s*$'
     let math = [0, 0]
-    if b:vimwiki_mathEnv != ""
-      call add(lines, "\\end{".b:vimwiki_mathEnv."}")
+    if s:current_math_env != ""
+      call add(lines, "\\end{".s:current_math_env."}")
     else
       call add(lines, "\\\]")
     endif

syntax/vimwiki_default.vim

@@ -4,9 +4,6 @@
 " Author: Maxim Kim <habamax@gmail.com>
 " Home: http://code.google.com/p/vimwiki/
 
-" placeholder for math environments
-let b:vimwiki_mathEnv = ""
-
 " text: $ equation_inline $
 let g:vimwiki_rxEqIn = '\$[^$`]\+\$'
 let g:vimwiki_char_eqin = '\$'

syntax/vimwiki_markdown.vim

@@ -4,9 +4,6 @@
 " Author: Maxim Kim <habamax@gmail.com>
 " Home: http://code.google.com/p/vimwiki/
 
-" placeholder for math environments
-let b:vimwiki_mathEnv = ""
-
 " text: $ equation_inline $
 let g:vimwiki_rxEqIn = '\$[^$`]\+\$'
 let g:vimwiki_char_eqin = '\$'

syntax/vimwiki_media.vim

@@ -4,9 +4,6 @@
 " Author: Maxim Kim <habamax@gmail.com>
 " Home: http://code.google.com/p/vimwiki/
 
-" placeholder for math environments
-let b:vimwiki_mathEnv = ""
-
 " text: $ equation_inline $
 let g:vimwiki_rxEqIn = '\$[^$`]\+\$'
 let g:vimwiki_char_eqin = '\$'