INSTALL: Clarify requirements.

PulseView depends on the libsigrok C++ bindings (not directly on
the libsigrok C library itself).
Add missing <cmath> #includes.

Some compilers throw warnings/errors otherwise:

  error: no member named 'abs' in namespace 'std'; did you mean '::abs'?"
android: Don't install unneeded Python files.
Linking QtSvg. This closes bug #369
Use <cstdlib> for std::abs() on integer datatypes.

The <cmath> #include needs to be used (only) for floating
point types.
CMakeLists.txt: Fix CMAKE_MODULE_PATH related issue.

Append to CMAKE_MODULE_PATH instead of overwriting it, in case it is
non-empty initially (which can happen e.g. if -DCMAKE_TOOLCHAIN_FILE is
used and the specified toolchain file sets CMAKE_MODULE_PATH).

Also, append to CMAKE_MODULE_PATH _after_ running "project(pulseview)",
since the latter would apparently reset CMAKE_MODULE_PATH again.

This should fix a MinGW-w64 build issue we're currently seeing:

  CMake Error at CMakeLists.txt:105 (include):
    include could not find load file:

      memaccess
CMakeLists.txt: Fix MinGW-w64 build issue related to QtSvg.

Specify the QtSvg requirement in the 'find_package(Qt4...)' line.

Also, change the linking order in the MinGW-w64 case, apparently the
build now fails without this.

  [...]/qt/plugins/imageformats/libqsvg.a(qsvgiohandler.o):\
			qsvgiohandler.cpp:(.text+0x571):
  undefined reference to `QSvgRenderer::load(QByteArray const&)'
  [...]
StoreSession: Removed commented code
.gitignore: Ignore vim .swo files
Header: Fixed mouse over coordinates
Trace: Renamed get_label_rect to label_rect
Trace: Correct shape of label_rect
Trace: Removed pt_in_label_rect
View: Replace compare_trace_v_offsets with a lambda
View: Simplified get_traces
Replaced duplicated code with Trace::get_y
DecodeTrace: Removed set_view
Pass in scale/offset as painting parameters
Refactored common row functionality into RowItem
RowItem: Renamed get_v_offset to v_offset