New option g:vimwiki_key_mappings to enable/disable key mappings.

All key mappings have the option of being disabled but the <Plug>
definitions are still available for user customization. Key sequences
are no longer overwritten if a mapping already exists. Fixes #671,
fixes #425.

autoload/vimwiki/u.vim

@@ -70,3 +70,22 @@ else
   endfunc
 endif
 
+" a:mode single character indicating the mode as defined by :h maparg
+" a:key the key sequence to map
+" a:plug the plug command the key sequence should be mapped to
+" a:1 optional argument to override the uniqueness checks
+"     this can be used to map different keys to the same <Plug> definition
+" This function maps a key sequence to a <Plug> command using the arguments
+" described above. If there is already a mapping to the <Plug> command or
+" the assigned keys are already mapped then nothing is done.
+function vimwiki#u#map_key(mode, key, plug, ...)
+  if a:0 > 0 && a:1 == 1
+    if maparg(a:key, a:mode) ==# ''
+      exe a:mode . 'map ' . a:key . ' ' . a:plug
+    endif
+  else
+    if !hasmapto(a:plug) && maparg(a:key, a:mode) ==# ''
+      exe a:mode . 'map ' . a:key . ' ' . a:plug
+    endif
+  endif
+endfunction

autoload/vimwiki/vars.vim

@@ -166,6 +166,12 @@ function! s:read_global_settings_from_user()
         \ 'hl_headers': {'type': type(0), 'default': 0, 'min': 0, 'max': 1},
         \ 'html_header_numbering': {'type': type(0), 'default': 0, 'min': 0, 'max': 6},
         \ 'html_header_numbering_sym': {'type': type(''), 'default': ''},
+        \ 'key_mappings': {'type': type({}), 'default':
+        \   {
+        \     'all_maps': 1, 'global': 1, 'headers': 1, 'text_objs': 1,
+        \     'table_format': 1, 'table_mappings': 1, 'lists': 1, 'links': 1,
+        \     'html': 1, 'mouse': 0,
+        \   }},
         \ 'list_ignore_newline': {'type': type(0), 'default': 1, 'min': 0, 'max': 1},
         \ 'text_ignore_newline': {'type': type(0), 'default': 1, 'min': 0, 'max': 1},
         \ 'links_header': {'type': type(''), 'default': 'Generated Links', 'min_length': 1},
@@ -250,6 +256,64 @@ function! s:normalize_global_settings()
       let g:vimwiki_global_vars.ext2syntax[ext] = 'media'
     endif
   endfor
+
+  " ensure key_mappings dictionary has all required keys
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'all_maps')
+    let g:vimwiki_global_vars.key_mappings.all_maps = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'global')
+    let g:vimwiki_global_vars.key_mappings.global = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'headers')
+    let g:vimwiki_global_vars.key_mappings.headers = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'text_objs')
+    let g:vimwiki_global_vars.key_mappings.text_objs = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'table_format')
+    let g:vimwiki_global_vars.key_mappings.table_format = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'table_mappings')
+    let g:vimwiki_global_vars.key_mappings.table_mappings = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'lists')
+    let g:vimwiki_global_vars.key_mappings.lists = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'links')
+    let g:vimwiki_global_vars.key_mappings.links = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'html')
+    let g:vimwiki_global_vars.key_mappings.html = 1
+  endif
+  if !has_key(g:vimwiki_global_vars.key_mappings, 'mouse')
+    let g:vimwiki_global_vars.key_mappings.mouse = 0
+  endif
+
+  " disable all key mappings if all_maps == 0
+  if !g:vimwiki_global_vars.key_mappings.all_maps
+    let g:vimwiki_global_vars.key_mappings.global = 0
+    let g:vimwiki_global_vars.key_mappings.headers = 0
+    let g:vimwiki_global_vars.key_mappings.text_objs = 0
+    let g:vimwiki_global_vars.key_mappings.table_format = 0
+    let g:vimwiki_global_vars.key_mappings.table_mappings = 0
+    let g:vimwiki_global_vars.table_mappings = 0 " kept for backwards compatibility
+    let g:vimwiki_global_vars.key_mappings.lists = 0
+    let g:vimwiki_global_vars.key_mappings.links = 0
+    let g:vimwiki_global_vars.key_mappings.html = 0
+    let g:vimwiki_global_vars.key_mappings.mouse = 0
+    let g:vimwiki_global_vars.use_mouse = 0 " kept for backwards compatibility
+  endif
+
+  " TODO remove these checks and the table_mappings and use_mouse variables
+  " backwards compatibility checks
+  " if the old option isn't its default value then overwrite the new option
+  if g:vimwiki_global_vars.table_mappings == 0
+    let g:vimwiki_global_vars.key_mappings.table_mappings = 0 && g:vimwiki_global_vars.key_mappings.table_mappings == 1
+  endif
+  if g:vimwiki_global_vars.use_mouse == 1 && g:vimwiki_global_vars.key_mappings.mouse == 0
+    let g:vimwiki_global_vars.key_mappings.mouse = 1
+  endif
+
 endfunction