Some major updates including heuristics

- Allow to define heuristics in heuristics.yaml
- Migrate all filetypes from vim beginning with "a"
- Remove enhanced cpp syntax (it was too slow to load)
- Use setf instead of set ft for setting filetype (faster)
- Override native hauristics with au!
- Add globbing of files for packages
- Replace predefined dirs with extra_dirs and ignored_dirs
- Allow to define proper order of packages with topological sort
- Fix powershell detection
- Lint and fix many packages.yaml issues
- etc etd

syntax/abc.vim

@@ -0,0 +1,55 @@
+if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'abc') == -1
+
+" Vim syntax file
+" Language:	abc music notation language
+" Maintainer:	James Allwright <J.R.Allwright@westminster.ac.uk>
+" URL:		http://perun.hscs.wmin.ac.uk/~jra/vim/syntax/abc.vim
+" Last Change:	27th April 2001
+
+" quit when a syntax file was already loaded
+if exists("b:current_syntax")
+  finish
+endif
+
+" tags
+syn region abcGuitarChord start=+"[A-G]+ end=+"+ contained
+syn match abcNote "z[1-9]*[0-9]*" contained
+syn match abcNote "z[1-9]*[0-9]*/[248]\=" contained
+syn match abcNote "[=_\^]\{,2}[A-G],*[1-9]*[0-9]*" contained
+syn match abcNote "[=_\^]\{,2}[A-G],*[1-9]*[0-9]*/[248]\=" contained
+syn match abcNote "[=_\^]\{,2}[a-g]'*[1-9]*[0-9]*"  contained
+syn match abcNote "[=_\^]\{,2}[a-g]'*[1-9]*[0-9]*/[248]\="  contained
+syn match abcBar "|"  contained
+syn match abcBar "[:|][:|]"  contained
+syn match abcBar ":|2"  contained
+syn match abcBar "|1"  contained
+syn match abcBar "\[[12]"  contained
+syn match abcTuple "([1-9]\+:\=[0-9]*:\=[0-9]*" contained
+syn match abcBroken "<\|<<\|<<<\|>\|>>\|>>>" contained
+syn match abcTie    "-"
+syn match abcHeadField "^[A-EGHIK-TVWXZ]:.*$" contained
+syn match abcBodyField "^[KLMPQWVw]:.*$" contained
+syn region abcHeader start="^X:" end="^K:.*$" contained contains=abcHeadField,abcComment keepend
+syn region abcTune start="^X:" end="^ *$" contains=abcHeader,abcComment,abcBar,abcNote,abcBodyField,abcGuitarChord,abcTuple,abcBroken,abcTie
+syn match abcComment "%.*$"
+
+
+" Define the default highlighting.
+" Only when an item doesn't have highlighting yet
+
+hi def link abcComment		Comment
+hi def link abcHeadField		Type
+hi def link abcBodyField		Special
+hi def link abcBar			Statement
+hi def link abcTuple			Statement
+hi def link abcBroken			Statement
+hi def link abcTie			Statement
+hi def link abcGuitarChord	Identifier
+hi def link abcNote			Constant
+
+
+let b:current_syntax = "abc"
+
+" vim: ts=4
+
+endif