Fix flags and parsing of flags

[GPMueller]

Closes #39 and #97.

• fixed parsing flags containing whitespace (e.g. -framework Cocoa)
• added -Wshadow to default flags
• changed optimization flag in debug build type from -O0 to -Og
• added address and undefined behaviour sanitizers to debug build
• added missing link flag in coverage build type
• added unit test for build types, including coverage build type

[codecov[bot]]

Codecov Report

Merging #99 into master will increase coverage by 0.55%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #99      +/-   ##
==========================================
+ Coverage   80.91%   81.47%   +0.55%     
==========================================
  Files          12       12              
  Lines         985      993       +8     
==========================================
+ Hits          797      809      +12     
+ Misses        188      184       -4

Impacted Files	Coverage Δ
clang_build/target.py	91.79% <100%> (+1.87%)	:arrow_up:

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