Move BufferView cached pointer out of LyXText:

Move BufferView cached pointer out of LyXText:

* LyXText
  - bv(), bv_owner, : deleted.
  - These methods now need a (Buffer const &) argument: getFont(), applyOuterFont(), getLayoutFont(), getLabelFont(), setCharFont(), setLayout(), singleWidth(), leftMargin(), rightMargin(), computeRowMetrics(), isMainText(), spacing(), isRTL(), cursorX(), rowBreakPoint(), setRowWidth(), labelFill(), labelEnd().
  - These methods now need a (BufferView const &) argument and are propably candidates for future removal when 1.6 is opened for development: redoParagraph(), x2pos(), getRowNearY(), getColumnNearX(), checkInsetHit(), setHeightOfRow().
  - recUndo(): now need a LCursor argument.

* CoordCache::get(LyXText const *, pit_type):
  - now const.
  - use const_iterator instead of iterator.

* FontIterator:
  - add (Buffer const &) argument to ctor
  - buffer_: new const reference to applicable BufferView.

* InsetBase
  - xo(), yo(), covers() and neverIndent() are now const.

* InsetText::setViewCache(): deleted

All other changes are due to the LyXText and InsetBase API changes.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@15618 a592a061-630c-0410-9148-cb99ea01b6c8