need weighted flavor of arb_progress

[westram]

Needed whenever doing 2 (or more) different kinds of things, where one takes far more time than another.

Example:

arb_progress initial("doing two diff things",2);
do_quick_thing(); // increments its own sub-progress
do_slow_thing(); // increments its own sub-progress

Progress runs quickly up to 50%, then it gets slow and always show too optimistic estimation.

Wanted style:

arb_weighted_progress initial("doing two diff things"); 
initial.inc_weighted(0.1);
do_quick_thing();
initial.inc_weighted(0.9); 
do_slow_thing(); // runs 9 times slower than do_quick_thing

Notes:

• arb_weighted_progress always shall run through range [0.0 .. 1.0]
• sum of all weights added using inc_weighted() shall sum up to 1.0
• provide method to retrieve leftover weight

[westram]

basic implementation with [18888]:

arb_progress progress(WEIGHTED, "title", phase1_fraction);

[westram]

examples demonstrating the effect of the weighted progress:

• r18889 = unweighted
• r18899 = weighted

(see commit message)

[westram]

by [18959]