Loosen slice checking against shape

Switch from checking against source shape to limits of slice,
match SliceND and Slice behaviour. Also add unit tests for 100%
coverage of those classes and replace fail with assertThrows,
and update Tycho to 3.0.5 and target platform to 2020-03 (aka 4.15)

.github/workflows/ci.yaml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [ '11' ]
+        java: [ '17' ]
     name: Java ${{ matrix.java }} compile
     steps:
     - uses: actions/checkout@v2

org.eclipse.january.test/META-INF/MANIFEST.MF

@@ -5,7 +5,7 @@ Bundle-SymbolicName: org.eclipse.january.test
 Bundle-Version: 2.3.3.qualifier
 Fragment-Host: org.eclipse.january;bundle-version="2.3.3"
 Bundle-RequiredExecutionEnvironment: JavaSE-1.7
-Require-Bundle: org.junit;bundle-version="[4.12.0,5.0.0)",
+Require-Bundle: org.junit;bundle-version="[4.13.0,5.0.0)",
  org.eclipse.january.asserts;bundle-version="2.3.2"
 Bundle-Vendor: Eclipse January
 Automatic-Module-Name: org.eclipse.january.test