Convert indentation tabs to spaces

[tmhglnd]

When loading a textfile with tabs used for indentation the indents are not converted to spaces correctly and there introduce an error in the result of the code on screen:

new synth sine name(s)
	set s note(notes 1) time(1/16) shape(1 300)
^^^^ tab of 4 spaces wide 

results in:

new synth sine name(s)
set s note(notes 1) time(1/16) shape(1 300) 

should result in:

new synth sine name(s)
    set s note(notes 1) time(1/16) shape(1 300)
^^^^ tab of 4 spaces wide