[Feature] Topology Cheker Plugin.
added files for topology plugin

modified cmakelists to add topology plugin folder

Conflicts:

	src/plugins/CMakeLists.txt

fixed issues in duplicate rule where zooming was not possible..renamed 'Test' to 'Rule'

fixed minimum segment length rule
renamed rules to meaningful descriptions

Added new rule "Must not have pseudos" for line vector layers.
Renamed rules to more understandable descriptions.
Handled WKB::MultilineStrings in line shapefiles in hanging lines rule that caused crashes.

"segments must have minimum length" rule now only checks if the geometry contains at least one short segment

added new Rule "Must Not Have Gaps"
removed unwanted indexing for some rules.
prepare commit run.

test commit

modified 'must not have gaps' rule.

updated calls to new vector api

more changes based on new api

fixed "must not have gaps rule"
fixed extent issues

changed dangle rule implementation

More rules added
-checkPointCoveredbyLineEnds
-checkPointInPolygon

new rules added
-point must be inside polygon
-polygon must contain point
-geometry must not be multipart

added rule 'checkyLineEndsCoveredByPoints'
renamed some rules
commented 'closer than tolerance rules' -performance issues
changed colors of error markers

changed visualization style of errors

changed rule paramters
validateExtent fixed to show only errors from within canvas extent
removed rule - polygons must contain feature
removed direct calls to geos api
prepare commit run

fixed missing icon in plugin manager

icons added. validateSelected option removed
fix gaps,overlaps for invalid goemetry errors by skipping
layer comboboxes display proper layers as per topologyrule
rule table now prevents duplicate entries
topology plugin:
- cleanups & fixes for warnings
- log messages
- translation strings
- return plugin category (fixes persistent loading)
[sextante] more tests
[sextante] changed how saga installation test is performed (now it uses the test data)
[sextante] changed version number (wasn't changed since last release) and min required qgis version
german translation update
deleted fixed Version in html

fixed Version is obsolete
Add a select by expression dialog.
Allow to change the current selection based on a QgsExpression
* Select (clear and select)
* Add to selection
* Remove from selection
* Select within selection (Intersect)
Add indexable vector layer cache
Major redesign of attribute table, codename: dual view
Add tests for attribute table / dual view
Fix issue #7169
If removing multiple attributes, remove the indices in descending order, so it does not get confused
Remove unneeded variable
Add tests for QgsVectorLayerCache
Fix: Check for existence of data provider to prevent segfault
Attribute table: Mark current edited in red so user is aware of autocommitted changes.
Quick fix.
The better approach would be to only change the color after changes have been made by the user
Fix rebase problems