Theme configuration for bold font style rendering

Implemented a nw theme configuration for the rendering of bold font
styles.

This commit adds the new `nord_bold` theme configuration to explicitly
toggle bold font rendering styles.
It is enabled by default when running for both in GUI and terminal mode.

The reason for this standard behavior is the fact that most terminals
and shells are capable to handle bold fonts.

GH-143

colors/nord.vim

@@ -72,11 +72,20 @@ let s:nord3_gui_brightened = [
   \ "#7b88a1",
 \ ]
 
+if !exists("g:nord_bold")
+  let g:nord_bold = 1
+endif
+
+let s:bold = "bold,"
+if g:nord_bold == 0
+  let s:bold = ""
+endif
+
 if !exists("g:nord_italic")
   if has("gui_running") || $TERM_ITALICS == "true"
-    let g:nord_italic=1
+    let g:nord_italic = 1
   else
-    let g:nord_italic=0
+    let g:nord_italic = 0
   endif
 endif
 
@@ -151,7 +160,7 @@ endfunction
 "+ UI Components +
 "+---------------+
 "+--- Attributes ---+
-call s:hi("Bold", "", "", "", "", "bold", "")
+call s:hi("Bold", "", "", "", "", s:bold, "")
 call s:hi("Italic", "", "", "", "", s:italic, "")
 call s:hi("Underline", "", "", "", "", s:underline, "")
 
@@ -214,7 +223,7 @@ if g:nord_cursor_line_number_background == 0
 else
   call s:hi("CursorLineNr", s:nord4_gui, s:nord1_gui, "NONE", s:nord1_term, "", "")
 endif
-call s:hi("Folded", s:nord3_gui, s:nord1_gui, s:nord3_term, s:nord1_term, "bold", "")
+call s:hi("Folded", s:nord3_gui, s:nord1_gui, s:nord3_term, s:nord1_term, s:bold, "")
 call s:hi("FoldColumn", s:nord3_gui, s:nord0_gui, s:nord3_term, "NONE", "", "")
 call s:hi("SignColumn", s:nord1_gui, s:nord0_gui, s:nord1_term, "NONE", "", "")
 
@@ -319,7 +328,7 @@ hi! link asciidocQuotedUnconstrainedEmphasized asciidocQuotedEmphasized
 hi! link asciidocURL markdownLinkText
 
 call s:hi("awkCharClass", s:nord7_gui, "", s:nord7_term, "", "", "")
-call s:hi("awkPatterns", s:nord9_gui, "", s:nord9_term, "", "bold", "")
+call s:hi("awkPatterns", s:nord9_gui, "", s:nord9_term, "", s:bold, "")
 hi! link awkArrayElement Identifier
 hi! link awkBoolLogic Keyword
 hi! link awkBrktRegExp SpecialChar
@@ -472,7 +481,7 @@ hi! link pythonBuiltin Type
 hi! link pythonEscape SpecialChar
 
 call s:hi("rubyConstant", s:nord7_gui, "", s:nord7_term, "", "", "")
-call s:hi("rubySymbol", s:nord6_gui, "", s:nord6_term, "", "bold", "")
+call s:hi("rubySymbol", s:nord6_gui, "", s:nord6_term, "", s:bold, "")
 hi! link rubyAttribute Identifier
 hi! link rubyBlockParameterList Operator
 hi! link rubyInterpolationDelimiter Keyword
@@ -482,10 +491,10 @@ hi! link rubyPseudoVariable Keyword
 hi! link rubyRegexp SpecialChar
 
 call s:hi("rustAttribute", s:nord10_gui, "", s:nord10_term, "", "", "")
-call s:hi("rustEnum", s:nord7_gui, "", s:nord7_term, "", "bold", "")
-call s:hi("rustMacro", s:nord8_gui, "", s:nord8_term, "", "bold", "")
+call s:hi("rustEnum", s:nord7_gui, "", s:nord7_term, "", s:bold, "")
+call s:hi("rustMacro", s:nord8_gui, "", s:nord8_term, "", s:bold, "")
 call s:hi("rustModPath", s:nord7_gui, "", s:nord7_term, "", "", "")
-call s:hi("rustPanic", s:nord9_gui, "", s:nord9_term, "", "bold", "")
+call s:hi("rustPanic", s:nord9_gui, "", s:nord9_term, "", s:bold, "")
 call s:hi("rustTrait", s:nord7_gui, "", s:nord7_term, "", s:italic, "")
 hi! link rustCommentLineDoc Comment
 hi! link rustDerive rustAttribute
@@ -525,7 +534,7 @@ hi! link vimFunction Function
 hi! link vimUserFunc Function
 
 call s:hi("xmlAttrib", s:nord7_gui, "", s:nord7_term, "", "", "")
-call s:hi("xmlCdataStart", s:nord3_gui_bright, "", s:nord3_term, "", "bold", "")
+call s:hi("xmlCdataStart", s:nord3_gui_bright, "", s:nord3_term, "", s:bold, "")
 call s:hi("xmlNamespace", s:nord7_gui, "", s:nord7_term, "", "", "")
 hi! link xmlAttribPunct Delimiter
 hi! link xmlCdata Comment
@@ -572,7 +581,7 @@ call s:hi("gitcommitSelectedFile", s:nord14_gui, "", s:nord14_term, "", "", "")
 
 " davidhalter/jedi-vim
 call s:hi("jediFunction", s:nord4_gui, s:nord3_gui, "", s:nord3_term, "", "")
-call s:hi("jediFat", s:nord8_gui, s:nord3_gui, s:nord8_term, s:nord3_term, s:underline."bold", "")
+call s:hi("jediFat", s:nord8_gui, s:nord3_gui, s:nord8_term, s:nord3_term, s:underline.s:bold, "")
 
 " NERDTree
 " > scrooloose/nerdtree
@@ -639,13 +648,13 @@ hi! link mkdDelimiter Keyword
 " > vimwiki/vimwiki
 if !exists("g:vimwiki_hl_headers") || g:vimwiki_hl_headers == 0
   for s:i in range(1,6)
-    call s:hi("VimwikiHeader".s:i, s:nord8_gui, "", s:nord8_term, "", "bold", "")
+    call s:hi("VimwikiHeader".s:i, s:nord8_gui, "", s:nord8_term, "", s:bold, "")
   endfor
 else
   let s:vimwiki_hcolor_guifg = [s:nord7_gui, s:nord8_gui, s:nord9_gui, s:nord10_gui, s:nord14_gui, s:nord15_gui]
   let s:vimwiki_hcolor_ctermfg = [s:nord7_term, s:nord8_term, s:nord9_term, s:nord10_term, s:nord14_term, s:nord15_term]
   for s:i in range(1,6)
-    call s:hi("VimwikiHeader".s:i, s:vimwiki_hcolor_guifg[s:i-1] , "", s:vimwiki_hcolor_ctermfg[s:i-1], "", "bold", "")
+    call s:hi("VimwikiHeader".s:i, s:vimwiki_hcolor_guifg[s:i-1] , "", s:vimwiki_hcolor_ctermfg[s:i-1], "", s:bold, "")
   endfor
 endif