More efficient loading for default syntax files

This change introduces header files for syntax files. The header
files only contain the filetype and detection info and can be
parsed much faster than parsing a full yaml file. To determine
which filetype a file is, only scanning the headers is necessary
and afterwards only one yaml file needs to be parsed. Use the
make_headers.go file to generate the header files. Micro expects
that all default syntax files will have header files and that
custom user syntax files may or may not have them. Resolving
includes within syntax has not yet been implemented. This
optimization improves startup time.

Ref #1427

internal/config/rtfiles.go

@@ -32,6 +32,7 @@ type RuntimeFile interface {
 
 // allFiles contains all available files, mapped by filetype
 var allFiles [NumTypes][]RuntimeFile
+var realFiles [NumTypes][]RuntimeFile
 
 // some file on filesystem
 type realFile string
@@ -85,6 +86,12 @@ func AddRuntimeFile(fileType RTFiletype, file RuntimeFile) {
 	allFiles[fileType] = append(allFiles[fileType], file)
 }
 
+// AddRealRuntimeFile registers a file for the given filetype
+func AddRealRuntimeFile(fileType RTFiletype, file RuntimeFile) {
+	allFiles[fileType] = append(allFiles[fileType], file)
+	realFiles[fileType] = append(realFiles[fileType], file)
+}
+
 // AddRuntimeFilesFromDirectory registers each file from the given directory for
 // the filetype which matches the file-pattern
 func AddRuntimeFilesFromDirectory(fileType RTFiletype, directory, pattern string) {
@@ -92,7 +99,7 @@ func AddRuntimeFilesFromDirectory(fileType RTFiletype, directory, pattern string
 	for _, f := range files {
 		if ok, _ := filepath.Match(pattern, f.Name()); !f.IsDir() && ok {
 			fullPath := filepath.Join(directory, f.Name())
-			AddRuntimeFile(fileType, realFile(fullPath))
+			AddRealRuntimeFile(fileType, realFile(fullPath))
 		}
 	}
 }
@@ -127,6 +134,12 @@ func ListRuntimeFiles(fileType RTFiletype) []RuntimeFile {
 	return allFiles[fileType]
 }
 
+// ListRealRuntimeFiles lists all real runtime files (on disk) for a filetype
+// these runtime files will be ones defined by the user and loaded from the config directory
+func ListRealRuntimeFiles(fileType RTFiletype) []RuntimeFile {
+	return realFiles[fileType]
+}
+
 // InitRuntimeFiles initializes all assets file and the config directory
 func InitRuntimeFiles() {
 	add := func(fileType RTFiletype, dir, pattern string) {
@@ -136,7 +149,7 @@ func InitRuntimeFiles() {
 
 	add(RTColorscheme, "colorschemes", "*.micro")
 	add(RTSyntax, "syntax", "*.yaml")
-	add(RTSyntaxHeader, "header", "*.hdr")
+	add(RTSyntaxHeader, "syntax", "*.hdr")
 	add(RTHelp, "help", "*.md")
 
 	initlua := filepath.Join(ConfigDir, "init.lua")