T1274: Slow down in curves/turns in route simulation + optimisations

Slowing down is based on max speeds and acceleration. Speed is limited
to 25m/s. Acceleration is 1.5m/s.
Max speed is set on points (m_lineStringInterpolated) based on formula.
(max speed before points is calculated so the acceleration won't be
exceeded)
On a simple turn (one point) the formula is (1-angleOfTurn/45)*maxSpeed.
On a curve the formula is more complicated. As a curve i treat every
group of consequent points with summarized distance smaller than 20m.
The max speed is set for the first point of curve. The formula is:
(1-sumOfAngles/45/(SummarizedDistance+10)*10)*maxSpeed.
As you can see if there is one point it can be treated as a curve,
because the formula is equal.
If there is a turn near (<25m) it won't accelerate.
Also I removed the m_lineStringInterpolated.insert lines. They were
forcing rewriting of QVector container inside m_lineStringInterpolated
every update.

Test Plan: I made several tests. I think the code behavior couldn't be
much better.

Reviewers: rahn, nienhueser

Maniphest Tasks: T1274

Differential Revision: https://phabricator.kde.org/D754