feat(log): add gitlog syntax file

syntax/gitlog.vim

@@ -0,0 +1,26 @@
+if exists("b:current_syntax")
+    finish
+endif
+
+syntax match gitlogGraph      contained /^[*|\\\/_ ]*/
+            \ nextgroup=gitlogHash
+syntax match gitlogHash       contained /\<\x\{7,64\}\>/
+            \ nextgroup=gitlogDate skipwhite
+syntax match gitlogDate       contained /\<\d\{4}-\d\{2}-\d\{2}\>/
+            \ nextgroup=gitlogAuthor skipwhite
+syntax match gitlogAuthor     contained /{[^}]\+}/
+            \ nextgroup=gitlogRef skipwhite
+syntax match gitlogRef        contained /([^)]\+)/
+syntax match gitlogLine
+            \ /^[*|\\\/_ ]*\x\{7,64}\s\+\d\{4}-\d\{2}-\d\{2}\s\+{[^}]\+}.*/
+            \ contains=gitlogGraph
+syntax match gitlogGraphLine /^[*|\\\/_ ]\+$/
+            \ contains=gitlogGraph
+
+highlight default link gitlogGraph      Comment
+highlight default link gitlogHash       GitSha
+highlight default link gitlogDate       GitDate
+highlight default link gitlogAuthor     GitAuthor
+highlight default link gitlogRef        Constant
+
+let b:current_syntax = "gitlog"