Fixed #115, #120, reverted changes to exporter as a workaround for VS Code

[omouraenko]

No description provided.

[omouraenko]

Fixed #115, #120. Reverted changes to exporter as a workaround for VS Code, not sure this is a good solution.

[omouraenko]

Looks like fix for #120 did not work correctly. Will take another look.

[omouraenko]

Second attempt seems to work for the following tests:

d =  sin(radians(90)) => \sin { \left( \operatorname{radians} 90 \right) }
d = radians(90)         => \operatorname{radians} { \left( 90 \right) }

Previous commit failed for the second test.

The initial code had the issue - 'insert_func_braces' set curly brackets before both left and right parentheses:

d =  sin(radians(90)) => \sin { \left( \operatorname{radians} 90 } \right)

Third commit just a clean up - removed extra 'return' calls.

[connorferster]

Thank you for this contribution!