Call getLineBreak with null XHyphenator unless TEXT_DRAW_WORDBREAK_HYPHENATION

So no longer instantiate XLinguServiceManager (which might e.g. bootstrap
Python) unless explicitly requested, which e.g. removes a noticable delay when
switching to the Options dialog's "Security" page (which causes size
calculations of FixedText controls that use TEXT_DRAW_WORDBREAK but not
TEXT_DRAW_WORDBREAK_HYPHENATION).

Change-Id: Ib0a28d3d7d7718faf6df7a138f5a86b8b2fd7713
Revert ScAccessibleCellBase::getCurrentValue to reutnr a numeric value again

b41332475783c31136673fb44cf4c411bb0148f8 "Integrate branch of IAccessible2" had
changed it to return a string, but that neither matched the documentation of
css.accessibility.XAccessibleValue nor did it satisfy JunitTest_sc_unoapi.  This
is the same underlying issue as 1cb1dca1260da2cea5b6800483e86a6d6b251844 "Revert
SwAccessibleCell::getCurrentValue to return a numeric value again" and needs
further clarification apparently.

Change-Id: Idb725724842ffa1aff811d66066912a22b2f2f6e
warning C4702: unreachable code

...and simplification

Change-Id: I652da35312522f452276116df11e548ba9231b53