Create 4 new formats enums rtl_math_StringFormat:
rtl_math_StringFormat_E1, rtl_math_StringFormat_E2,
rtl_math_StringFormat_G1, rtl_math_StringFormat_G2
to 1 or 2 digits in exponent for scientific notation.

Set General format to use rtl_math_StringFormat_E2.
Set trendline equation in status bar to use rtl_math_StringFormat_E1

Change-Id: I41466a6d4ba808ba5b9b38ba252b37c6b4560f12
Reviewed-on: https://gerrit.libreoffice.org/14562Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>