Make the output of \inputencoding commands (and the change of output

Make the output of \inputencoding commands (and the change of output
encodings) more fine grained: From paragraph level to individual character
level. The inputenc package supports that since at least 2000.

	* src/insets/insetbase.h
	(latex): Document the differences between output to a string stream
	and a file stream

	* src/buffer.h
	(writeLaTeXSource): ditto

	* src/output_latex.h
	(latexParagraphs): ditto
	(switchEncoding): new function to change the encoding of a stream
	(and output \inputencoding commands)

	* src/paragraph_pimpl.C
	(Paragraph::Pimpl::simpleTeXSpecialC): Adjust to latexWriteEndChanges
	changes

	* src/support/docstream.[Ch]
	(setEncoding, operator<<): New stream modifier that changes the
	encoding of file streams

	* src/lyxfont.[Ch]
	(LyXFont::latexWriteStartChanges): Change stream encoding if needed
	(LyXFont::latexWriteEndChanges): Change stream encoding if needed

	* src/lyxfont.h
	(public:):

	* src/paragraph.C
	(Paragraph::simpleTeXOnePar): Adjust to latexWriteStartChanges and latexWriteEndChanges changes
	(bool Paragraph::simpleTeXOnePar):
	(bool Paragraph::simpleTeXOnePar):
	(bool Paragraph::simpleTeXOnePar):
	(bool Paragraph::simpleTeXOnePar):
	(bool Paragraph::simpleTeXOnePar):

	* src/output_latex.C
	(TeXOnePar): Remove the ugly hack to for wencoding changes and use
	switchEncoding instead. A nice side effect is that the old hack would
	not work if the main language encoding is latin1 and a character
	would be mapped to a cedilla in the "fake ucs4" encoding, because
	iconv refuses to convert such a character to latin1, although it
	exists in latin1 (it wants to attach it to a base character).

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@16633 a592a061-630c-0410-9148-cb99ea01b6c8