RM2SF Change the typeface of non-math text to sans-serif

Changes the typeface of non-math text with latex interpreter from roman to sans-serif.

RM2SF changes the typeface of non-math text with latex interpreter from
roman (serif) to sans-serif. This is needed because the latex interpreter
typesets both math and text in roman irrespective of the font
specification. Therefore RM2SF places each non-math part of the text
inside \textsf{}.

RM2SF replaces, by \textsf{STR}, each non-math part STR of all text
objects in the current figure whose interpreter is set to latex.

RM2SF(FIG) applies to text objects in figure with handle FIG.

RM2SF(AX) applies to text objects in axes with handle AX.

RM2SF(TX) applies to text objects with handles specified in vector TX.

Example:

tx(1) = text(0.2,0.8, 'square of \$x\$ is $x^2$');
tx(2) = text(0.3,0.6, {'sine of $\theta$'; 'is $\sin \theta$'});
tx(3) = text(0.2,0.4, 'cube of $x$ is $x^3$');
tx(4) = xlabel('time $t$ here');
tx(5) = ylabel('concentration {\it C(t)} here', 'FontSize', 20);
set(tx(1:4), 'FontSize', 20 , 'Interpreter', 'latex')
rm2sf(tx([1 2 4]))