Deprecating .rotate() and introducing .rotation() context manager

[Lucas-C]

Minimal Python code reproducng the issue with the current rotate method:

pdf = fpdf.FPDF()
pdf.add_page()
pdf.rotate(90)
pdf.image("lena.gif")
pdf.add_page()
pdf.rotate(90)
pdf.image("lena.gif")
pdf.output("out.pdf")

The generated file contains the following stream:

2 J
0.57 w
Q
q 0.00000 1.00000 -1.00000 0.00000 28.35 813.54 cm 1 0 0 1 -28.35 -813.54 cm
q 128.00 0 0 128.00 28.35 685.54 cm /I1 Do Q

Notice the invalid leading Q operator.

This issue was detected using Datalogics PDF Checker

[Lucas-C]

This was ported to fpdf2: https://github.com/alexanderankin/pyfpdf/blob/master/CHANGELOG.md#210---2020-12-07