This commit transfer the ErrorList handling from LyXView to Buffer. It also removes...

This commit transfer the ErrorList handling from LyXView to Buffer. It also removes the need for the error signal and simplify the kerbel <-> frontend communication. I think it should speed-up _significantly_ the latex compilation for example in case of problematic files.

TODO 1: All occurrences of "LyXView::showErrorList()" in the "kernel" should be replaced by a boost signal emission (Buffer::errors()). This signal is already connected to this showErrorList() slot.

TODO 2: The ErrorList mechanism is used wrongly in a number of place, most notably in "Converter.C". Instead of replacing the ErrorList in the "Buffer" class, the "Converter" class should maintain its own list instead and connect directly to the LyXView::showErrorList() slot.

Buffer:
* errorList_: new private member and associated access methods.
* setErrorList(): new accessor method.
* addError(): apend an error to the errorList_.
* error(): deleted.
* errors(): new boost signal, unused for now. Shall be used instead of LyXView::showErrorList().

LyXView:
* getErrorList(), addError(), errorlist_, errorConnection_: deleted.
* errorsConnection_: new boost connection for the Buffer::errors() signal.

lyx_main.C:
* LyX::exec2(): manually print all errors.

BufferView.h: remove unneeded ErrorList forward declaration.

BufferView::pimpl::menuInsertLyXFile(): delete Buffer::error() connection and add a FIXME comment

text.C: Use Buffer::addError() instead of Buffer::error() signal emission.

ControlErrorList.C: get the ErrorList from the Buffer instead of LyXView

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@14467 a592a061-630c-0410-9148-cb99ea01b6c8