Load covington later

This solves a loading order conflict with beamer-article.

lib/layouts/linguistics.module

@@ -55,9 +55,11 @@ Style Numbered_Example_(multiline)
 	Preamble
 	% Backwards compatibility with covington < 1.1
 	% This code can be removed eventually
-	\@ifundefined{covexample}{%
-	    \newenvironment{covexample}{\begin{example}}{\end{example}}%
-	}{}
+	\AtBeginDocument{%
+		\@ifundefined{covexample}{%
+		    \newenvironment{covexample}{\begin{example}}{\end{example}}%
+		}{}
+	}
 	EndPreamble
 	Category              Linguistics
 End
@@ -88,9 +90,11 @@ Style Numbered_Examples_(consecutive)
 	Preamble
 	% Backwards compatibility with covington < 1.1
 	% This code can be removed eventually
-	\@ifundefined{covexamples}{%
-	    \newenvironment{covexamples}{\begin{examples}}{\end{examples}}%
-	}{}
+	\AtBeginDocument{%
+		\@ifundefined{covexamples}{%
+		    \newenvironment{covexamples}{\begin{examples}}{\end{examples}}%
+		}{}
+	}
 	EndPreamble
 End
 
@@ -105,16 +109,18 @@ Style Subexample
 	Preamble
 		% Backwards compatibility with covington < 1.6
 		% This code can be removed eventually
-		\@ifundefined{covsubexamples}{%
-			\newenvironment{covsubexamples}{%
-				\addtolength{\examplenumbersep}{-0.5em}%
-				\begin{covexample}%
-				\begin{enumerate}
-				\renewcommand\theenumi{\alph{enumi}}
-				\renewcommand\labelenumi{(\theenumi)}
-				\renewcommand\p@enumi{\theequation\,}}%
-			{\end{enumerate}\end{covexample}}
-		}{}
+		\AtBeginDocument{%
+			\@ifundefined{covsubexamples}{%
+				\newenvironment{covsubexamples}{%
+					\addtolength{\examplenumbersep}{-0.5em}%
+					\begin{covexample}%
+					\begin{enumerate}
+					\renewcommand\theenumi{\alph{enumi}}
+					\renewcommand\labelenumi{(\theenumi)}
+					\renewcommand\p@enumi{\theequation\,}}%
+				{\end{enumerate}\end{covexample}}
+			}{}
+		}
 	EndPreamble
 End
 

src/BufferParams.cpp

@@ -2303,6 +2303,10 @@ bool BufferParams::writeLaTeX(otexstream & os, LaTeXFeatures & features,
 		os << "\\usepackage{xunicode}\n";
 	}
 
+	// covington must be loaded after beamerarticle
+	if (features.isRequired("covington"))
+	    os << "\\usepackage{covington}\n";
+
 	// Polyglossia must be loaded last ...
 	if (use_polyglossia) {
 		// call the package

src/LaTeXFeatures.cpp

@@ -971,7 +971,6 @@ char const * simplefeatures[] = {
 	// "cancel",
 	"ascii",
 	"url",
-	"covington",
 	"csquotes",
 	"enumitem",
 	"endnotes",