fix bounding box, force 1st absolute M

[herrstrietzel]

Referring to issue 47: "getPathBBox () in versions":

The latest build 2.1.8 struggles with pathdata starting with pseudo-relative M commands - causing the bbox calculation to fail:

M 77.7553 122.1843 a 15.6631 5.5 45 0 1 14.9646 7.1864 l 8.053 8.053 a 15.6631 5.5 45 0 1 -7.7782 7.7782 l -8.053 -8.053 a 15.6631 5.5 45 0 1 -7.1864 -14.9646

would return the expected bbox of width:31.529978953390923, height:31.529978953390895

m 77.7553 122.1843 a 15.6631 5.5 45 0 1 14.9646 7.1864 l 8.053 8.053 a 15.6631 5.5 45 0 1 -7.7782 7.7782 l -8.053 -8.053 a 15.6631 5.5 45 0 1 -7.1864 -14.9646

would fail and return an incorrect one width:108.62229440861523, height:153.0512944086152]

This also applies to cubic approximations like

m77.7553 122.1843
C 79.9 120.04 86.6 123.25 92.72 129.37
L 100.77 137.42
C 106.88 143.54 110.11 150.24 107.96 152.39
C 105.81 154.54 99.11 151.31 92.99 145.2
L 84.94 137.15
C 78.82 131.03 75.61 124.33 77.76 122.18

Forcing the first M command to use an uppercase type identifier fixes this issue.
However, this quick fix may be more suitable in the getPathBBox.ts

See codepen
2.1.8
2.1.8.1 - fix

[thednp]

@herrstrietzel
Thank you for the contribution, I've patched this and I will publish 2.1.8 then.

PS: Sorry I didn't merge your PR, there was a problem with the tests.