Introduce linting

[mmacata]

Initial lint status:

1     E101 indentation contains mixed spaces and tabs
1     E116 unexpected indentation (comment)
1     E117 over-indented (comment)
10    E122 continuation line missing indentation or outdented
41    E124 closing bracket does not match visual indentation
1     E125 continuation line with same indent as next logical line
99    E127 continuation line over-indented for visual indent
132   E128 continuation line under-indented for visual indent
1     E221 multiple spaces before operator
14    E225 missing whitespace around operator
19    E231 missing whitespace after ':'
12    E251 unexpected spaces around keyword / parameter equals
1     E261 at least two spaces before inline comment
35    E265 block comment should start with '# '
1     E266 too many leading '#' for block comment
2     E271 multiple spaces after keyword
51    E302 expected 2 blank lines, found 1
10    E303 too many blank lines (3)
1     E305 expected 2 blank lines after class or function definition, found 1
1576  E501 line too long (85 > 79 characters)
5     E722 do not use bare 'except'
277   F401 '.add_dimension_process' imported but unused
5     F403 'from openeo_grass_gis_driver.utils.process_graph_examples_v10 import *' used; unable to detect undefined names
34    F405 'FILTER_BBOX' may be undefined, or defined from star imports: openeo_grass_gis_driver.utils.process_graph_examples_v10
9     F821 undefined name 'vector_object'
45    F841 local variable 'rn' is assigned to but never used
1     W191 indentation contains tabs
15    W293 blank line contains whitespace
7     W605 invalid escape sequence '\-'
2407

Status after this PR:

526   E501 line too long (90 > 79 characters)
14    F821 undefined name 'randint'
5     F841 local variable 'p_target_dimension' is assigned to but never used
545

[neteler]

I have quickly checked all 19 commits, looks good to me. Thanks for your efforts!

[metzm]

Please merge