fix jlreq abstract layout and adapt Chinese docs for unicode engines

jlreq layout defined the abstract environment to be boxed
in the preamble. Doing any kind of typesetting before
all the setup has finished is error prone and may lead to
wrong output (wrong fonts for example). The correct
place to put the abstract code is right before \maketitle.

The Chinese docs loaded the ctex package in case system fonts
were used. Now, with the new support for languages with babel
and polyglossia it is no longer necessary and creates collisions.

lib/doc/zh_CN/Intro.lyx

@@ -5,13 +5,6 @@
 \save_transient_properties true
 \origin /systemlyxdir/doc/zh_CN/
 \textclass article
-\begin_preamble
-% Chinese localization
-\@ifpackageloaded{fontspec}%
-{\usepackage{ctex}}% ctex with non-TeX fonts
-{%\usepackage[UTF8]{ctex}% error with font setup (missing font?)
-}
-\end_preamble
 \use_default_options true
 \maintain_unincluded_children no
 \language chinese-simplified

lib/doc/zh_CN/Tutorial.lyx

@@ -5,13 +5,6 @@
 \save_transient_properties true
 \origin /systemlyxdir/doc/zh_CN/
 \textclass book
-\begin_preamble
-% Chinese localization
-\@ifpackageloaded{fontspec}%
-{\usepackage{ctex}}% ctex with non-TeX fonts
-{%\usepackage[UTF8]{ctex}% error with font setup (missing font?)
-}
-\end_preamble
 \options cjk
 \use_default_options true
 \maintain_unincluded_children no

lib/layouts/jlreq-common.inc

@@ -94,7 +94,7 @@ End
 
 Style Abstract_over_Columns
 	CopyStyle			Abstract
-	InPreamble			1
+	InTitle               		1
 	LabelString			"Abstract"
 	Category			FrontMatter
 	LatexType			Command