add setting to temporarily override ignorecase

fixes #134

doc/supertab.txt

@@ -27,6 +27,7 @@ Supertab                                    *supertab*
     Preselecting the first entry            |supertab-longesthighlight|
     Mapping <cr> to end completion          |supertab-crmapping|
     Auto close the preview window           |supertab-closepreviewonpopupclose|
+    Keyword completion ignore/match case    |supertab-completecase|
     Completion Chaining                     |supertab-completionchaining|
 
 ==============================================================================
@@ -375,6 +376,25 @@ g:SuperTabClosePreviewOnPopupClose (default value: 0)
 When enabled, supertab will attempt to close vim's completion preview window
 when the completion popup closes (completion is finished or canceled).
 
+
+Completion ignore/match case        *supertab-completecase*
+                                    *g:SuperTabCompleteCase*
+
+g:SuperTabCompleteCase (default value: 'inherit')
+
+When issuing completions (keyword and potentially others), the value of your
+|'ignorecase'| setting will determine what results are returned based on
+whether or not you've chosen to ignore case or not. However, you may have
+|'ignorecase'| set or unset for other reasons and don't want that value
+considered when using insert completion. SuperTab allows you temporarily
+override |'ignorecase'| by setting g:SuperTabCompleteCase to either 'ignore'
+or 'match' depending on whether you want to always ignore or match case when
+using insert completion.
+
+Note: third party omni/user completion plugins may or may not honor
+|'ignorecase'|. If they do not, then you can probably contact them to add that
+support.
+
 Completion Chaining                  *supertab-completionchaining*
 
 SuperTab provides the ability to chain one of the completion functions

plugin/supertab.vim

@@ -139,6 +139,10 @@ set cpo&vim
     let g:SuperTabUndoBreak = 0
   endif
 
+  if !exists("g:SuperTabCompleteCase")
+    let g:SuperTabCompleteCase = 'inherit'
+  endif
+
 " }}}
 
 " Script Variables {{{
@@ -469,6 +473,23 @@ function! SuperTab(command) " {{{
         return "\<c-g>u" . complType
     endif
 
+    if g:SuperTabCompleteCase == 'ignore' ||
+     \ g:SuperTabCompleteCase == 'match'
+      if exists('##CompleteDone')
+        let ignorecase = g:SuperTabCompleteCase == 'ignore' ? 1 : 0
+        if &ignorecase != ignorecase
+          let b:supertab_ignorecase_save = &ignorecase
+          let &ignorecase = ignorecase
+          augroup supertab_ignorecase
+            autocmd CompleteDone <buffer>
+              \ let &ignorecase = b:supertab_ignorecase_save |
+              \ unlet b:supertab_ignorecase_save |
+              \ autocmd! supertab_ignorecase
+          augroup END
+        endif
+      endif
+    endif
+
     return complType
   endif